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Full text of "Concrete and constructional engineering"

AS r y 



CONCRETE 

AMD 

CONSTRUCTIONAL ENGINEERING 

VOL. X. 1915. Nos. 1 to 12. 

/I MONTHLY JOURNAL FOR ENGINEERS, 
ARCHITECTS, SURVEYORS & CONTRACTORS 
and all interested in CEMENT, CONCRETE, 
REINFORCED CONCRETE, FIRE-RESISTING 
CONSTRUCTION and STRUCTURAL STEEL. 



VOLUME X. 




All Rights Reserved 



Published at 4 Catherine Street, Aldwych, London, IV. C. 
Editorial Offices at : 8 Waterloo Place, Pall Mall, London, S.IV. 

1915 



CONCRETE 









Volume X. 1915. 

Published at 4, Catherine Street, Aldwych, London, W.C. 

Editorial Offices at: 8, Waterloo Place, Pall Mall, London, S.W. 






INDEX. 

PAGE 



PAGE 



BOOKS, NEW : 

Advisory Committee on Rural Cottages, 

Report of the 215 

British Standard Specification for Portland 

Cement. Revised 1915 258 

Concrete Road £ and Kerbs 107 

Concrete and Steel Construction (Part I.). 

Buildings. Ey H. T. Eddy and C. A. P. 

Turner 106 

rete Stone Manufacture. By Harvey 

Whipple 259 

Construction of Masonry Dams. By Chester 

YV. Smith ... 424 

I :u r n of Steel Bridges. By F. C. Kunz, 

C.E 476 

Engineering Society of China : The Report 

of the Special Committee on Reinforced 

Concrete 54 

<nal Physical Laboratory : Report for 

the Year 1514-15 47 6 

Plain and Reinforced Concrete Arches. By 

J. Melan 424 

ipture and Expansion of British Trade : 

The Building Trade 477 

forced Concrete in Practice. By A. 

A 1 ban II. Scott ( 308 

Spon's Architect's and Builder's Pocket 

Price Book 258 

Str'-ngth of Materials, The. By E. S. 

Andrew- 590 

Structural Engineer's Handbook. By Milo 

Ketchum, C.E 106 

I ernary System, The 259 

Text-book on Practical Mathematics for 

Advanced Technical Students. By H. 

Leslie Mann, B.Sc. 648 

Wind Stresses in the Steel Frames of 

Office Buildings. By W. M. Wilson and 

( \ A. Maney 590 

CEMENT : 

Kritisli Standard Specification for Portland 

tnent 597 

Durability of Cement Drain Tiles in Alkali 

Soils 599, 628 

raphical Model Constructed in Cement, 
A 



EDITOR1 *L NO I ES : 

iiriti-h Standard Specification for Portland 
I • ment 

Cement Drain 'lib- in Alkali Soils 

Concrete Institute, The. Jin Annual Meet 
Di« 

Construction arid Protection of Buildings 
in Relation to Fi re 

Contractors and Reinforced Concrete 

Earthquake Districts, Reinforced <'on<r't' 
in 

Economy in Reinforced Concrete Construc- 
tion 

Government Certification of Cement in 
tendt d for Export 

I nfluenc <■ ot th< War, 'I in- 

London Bui Iding Acts, 'I be 

1. ndon County Council Regulations for Re- 
inforced Concrete Construction 



626 



597 

599 

321 

02 
OOO 

543 



.177 



Microscope in the Study of Concrete, The 272 

Municipal Works, Concrete and Reinforced 
Concrete in 

Obituary Notice : The late Mr. Edward 
Coignet 

Oil-mixed Concrete 

Research Work, The Need for 

Rural Housing 

Shipbuilding Work, Portland Cement Con- 
crete and Cement Concrete in ... ... 482 

Wind Pressure, The Question of 219 



61 



43i 
"5 



29 

283 



169 

575 

63 



GENERAL : 

Action of Boiling Water on Concrete, The. 
By Prof. E. R. Matthews, A.M.Inst.C.E. 

Annual General Meeting : Concrete Institute 

Bridges on the Columbia Highway, U.S.A., 
Some Concrete. By K. P. Billner 404 

Bridge near Merthyr, Reinforced Concrete 323 

Bristol General Hospital, Reinforced Con- 
crete at the. By Albert Lakeman, M.S. A. 

Buoys and Sinkers, Concrete ... 

Caissons at Sunderland Docks, Reinforced... 

Column Bending Moments in Frame Con- 
struction. By Ewart S. Andrews, B.Sc, 
Eng. (Lond.) 10, 68 

Concrete Columns and Their Cost. By 
Rohintan M. Fram Mirza 132 

Concrete Institute, The 122, 283, 609 

Concrete for Ornamental Garden Work ... 32 

Concrete Road Construction ... ... ... 146 

Concrete Roads 560 

Correspondence (see Memoranda), also : 

108, 309, 536 

Cottages at Crayford, Concrete 137 

Crossley Lads' Club, Manchester, Rein- 
forced Concrete at the 

Dam of Medina Valley Irrigation Project 
In Texas, Main Concrete Dam and 
Diversion 

Deep Water Concreting through a Tube. 
By E. B. Van de Greyn 

Determination of the Position of the 
Neutral Axis in a Tee-Beam by the Aid 
of SiniDle Graphs, The. By H E. 
Lance Martin, B.Sc. (Lond.) 

Durability of Cement Drain Tiles in Alkali 
Soils. By R. J. Wig and G. M. Williams 628 

Earthquake Districts, Reinforced Concrete 
in. Regulations by the Ministry of Public 
Works, Rome 

Effect of Reinforced Concrete upon Archi- 
tectural Design, The. By Frank N. 
Heaven, A R.I.B.A 

Empire and India Houses, Kingsway. By 
A. Lakeman, MS A 

Enquiries (See Memoranda). 

Fixing Temporary Blinds to Reinforced 
Concrete Beams 

Ford Motor Co., Chicago. A Reinforced 
Concrete Building for the 

Gas Works at Keilehaven, Rotterdam, 
Reinforced Concrete in the New 

Gate Structures for Irrigation Canals. 

Com red- in ... 
Geographical Model Constructed in Cement, 

A 



483 



126 



39 



333 



237 



433 



*73 



337 



45 S 
696 



Halifax I >> i an ' " rminali Bj \ I 
Dyer, t.M.lnit.< I 

High Stn ngth Com i 
throng! I ' Surfac< 

,i Mixing Water. By Nathan 

1 uilin ii. . l.m< I In) 

Ewai 
[- land 



Produi <l 
I John 



Bi .in I '< H' i i low Bj 
i S Andrews, B.Sc, Eng 
Sit. Hot< I, I he B> Ubi ri 



Lak< 



I lollll .111.1 

Aii 1 ostam < 

( '.III! 1-1. 



I 

Ml ... 

Regula 

•14'. .S"-\ 



' .i.s 
545 



.,i Defectivt 
fohnson ... 

Proportioning 
By Nathan C. 



..ii Const i in tion, 



in. in. M S \ 

itning "ii .i Steel 
i,,i . , ,i Com rett Walls 

1. moon's R< inforced 
i ions (,iv r, \ ised) 

Marini Drive, I xmouth ... 

M. . nanical Disinti gration 
Con. i . tea By Nathan C 

M i, i ,.-. op< -i- an Aid ii 
Concrete for Stn ngth. 
Johnson 

M in oscope as a Ch< i k 
By Nathan C. Johnson 

Microscope shows importance oi Mixing 
a- a Factor in making Strong Cm. ml 

Microscope in the Study and investigation 
of Concrete, 1 Ik-. By Nathan C. John- 
son 288, 348, 398, 448, 514, 615 

Moment ol inertia of Reinforced Concreti 
Sections. By John Davenport, M.Sc. 

New Exchange Buildings, Swansea, The ... 

Oil Mixed Portland Cement Concrete 

Ornamental Garden Work, Concrete for ... 

Padstow Station, Reinforced Concrete 
Road 

Patents relating to Concrete, Recent 
British »3, '87, 344, 508 

Pier at Pad^tow, Reinforced Concrete. By 
Sir G. Croydon Marks, M.P.. 
A M.Inst. C.E. 

Port Dundas Distillery. By Albert Lake- 
man, M.S. A. 

Power House, New Zealand, Reinforced 
Concrete. By H. C. Gayford 

Presidential Address, Concrete Institute ... 

Problems in the Theory of Construction 

10, 68, 230, 393, 

Quay Wall, Southampton, Reinforced Con- 
crete 

Racecourse Stand, Cheltenham, Reinforced 
Concrete. By Albert Lakeman, M.S. A. ... 

Regent Palace Hotel 

Roads, Concrete 

Road Construction, Concrete 

Road at Mountnessing, Essex ... 

Road at Whitefriars, Chester, The New 

Roberts Lane, Saltney, Chester 

Semi-circular Arch carrying its own 
weight only. By Ewart S. Andrews, B.Sc. 

Standard Specification for Reinforced Con- 
crete Work, A 

War in Relation to Building, The 

Wharf and Jetty for the Port Talbot 
Railway and Dock Co., New Reinforced 
Concrete 

What is a 1:2:4 Concrete? By H. C. 
Johnson 

Wind Stresses in Building Frames 

INDUSTRIAL NOTES: 

Interlocking Blocks, New System of ... ... 533 

Steel Piling ... ... ... ... ... ... 260 

New Method of Reinforced Concrete Sheet 

Piling, A 310 

MEMORANDA : 

Acid Towers Built of Concrete 267 

Aeroplanes, Reinforced ... ... ... ... 538 

American Concrete Institute ... ... ... 57 

Association of Consulting Engineers (In- 
corporated), The 57 

Belfast Harbour Equipment ... ... ... 112 

Blocks at Fishguard, Concrete 427 

Blyth Harbour, Improvements at 521 

Bridge, Devon 375 

Bridge, New, Essex 596 

Bridges, Thames, New Reinforced Concrete 112 

Bristol Docks ... ... ... ... ... ... 112 

British Engineers' Association, The ... ... 57 

Canadian • Engineering Operation, A ... 596 
"Cathedral in Reinforced Concrete at 

Georgetown, Demerara 59 



93 

5*7 
563 

348 



398 
448 

5' ] 



179 

117 

492 

33 

565 



38' 

17 
609 

555 

233 

3 
545 
560 
146 
562 
56i 
560 

230 

122 

243 

601 

«5 
555 



1 V.I. 

539 

I 
54* 



1 . m. ni .1 Vnti Sand Blast 

Citj and Gulldi ol London Insti) ut< , 

1 '■ pai 1 in- ni "i l ■ ■ bnology 

C,l licry Klectrh Lamp Rooms 

1 lank 1 rani if Routi , 1 

.ui.l .1 ii.il i mil. • "i 

1 titute, Mi' 
Concreti Scow bai withst 1 , ' jreai Hard 

>< 1 V i< < 

reti Surfact ... 

< ..ni 1 .1. 1 \. ■ • pt( -I 

Contrai 1 ' >pen •'■*. '•-•' 

■ 1 1. .i.l, ( on. ret( ' '3 

Draining Land by Wells, < on< reti I >rain 

'i ad «3 

Dundei 1 Hall 5^ 

Lit. 1 t.i.il S< aling 0< Wat. 1 I Jam by 

c. mentation. 1 m 

Engine Foundation, How to Build an ... 655 
Enquiries ••■ ■•• ••• •■■ ••• 59 

Erecting Ga 1 Engines 593 

Errata Notes 37<J> 43°i 4«" 

Expenditure on Public Works ... 317 

Fires due to Air Rai Is 

Fishguard Harbour Works 
Flagpole at Panama, Reinforced 



d< :i, Rein for< ed 



( ..in 1 > t> 
( cm rete 



|I5 

''Si 

592 

479 

653 

• 655 

... 049 
... 050 
... 264 
1 ',4 
104, 264 
for 



Tank with Con- 
a Steam Launch, 



respect to 



the 
or 



Footbridge, Nea 

I iug Frames in Reinforced Concreti 
Grape Vine Posts of Concrete .. 
Hostile Air Raids, Police Warning ... 
Houses for the Working Classes 

Institute ol Arbitrators 

Institution of Civil Engineers, The ... 

Iron and Steel Institute 

Keel of a Sailing Craft. Concrete 

the 

Kehoe v. Simplex Concrete Piles, Ltd. 

King George Hospital, The 

Law and Engineering 

Lighthouse, Reinforced Concrete 

Lining the Shafts of Mines, a Downward 

Sy-tem 
Lining large Steel Coal 

crete 

Lining for Steel Hull of 

Concrete 

Literary Note 

Loans for Public Work 
L.C.C. Regulations with 

Construction of Buildings wholly 

part'y of Reinforced Concrete, The 

Loughor Bridge 

Manchester Municipal School of Tech- 
nology, The. 

Microscope in the Study of Concrete, The 

Midland Institute, Birmingham 

Motor Track in America, First Concrete ... 
National Road Conference and Exhibition, 

1915, The 

National Road Exhibition 

Nairobi Stock Exchange Buildings 

New Pennsylvania Elevator of Reinforced 

Concrete at Philadelphia 

Oil-mixed Concrete Tests 

Pa>ing Streets with Concrete 

Picture Houses, Reinforced Concrete 
Pictures Showing Concrete Construction, 

Moving 

Pier at Tiree, Long Concrete 

Pipes, Reinforced Concrete 

Plugs, Concrete 

Police Warning, Hostile Air Raids 

Polish on Concrete Surfaces 

Porch at Elkhart, Indiana, A Concrete 
Port of London Authority, New Cold Stores 
Proposed New Works. ..267, 319, 375, 429, 541, 657 

Publications Received 114, 166, 218, 541 

Purifier House at the Poole Gas Works, 

Concrete for .. 

Reinforced Concrete Regulations 

River Trent, the Improvement of the 
Roads at Chisel don, Wilts, Reinforced 

Concrete 

Road Making, Cheaper 

Safes. Reinforced Concrete for Bank 

San Erancisco Shore Protection 

Shanghai Electricity Works 

Sleepers for Tramways, Reinforced Con- 
crete 112 

Slipway for Motor Boats, the Construction 

of a 

Small Holdings, Concrete Buildings for ... 

Sma'lpox Hospital, Whitehaven 

Surface Imperfections 



539 

1 ''5 
582 
54i 

650 

58 

59 
3«9 

375 



426 
i65 

538 
559 
649 
566 

3i5 
429 
317 

264 
651 
59i 
375 

595 
592 
541 
480 
649 
541 
595 
592 



59 
559 
165 

539 
539 
654 
654 
654 

373 

112 
316 

532 
480 



Works ... 
at Hudson, 



Wisconsin, 



PAGE 

Tender- I I 

Te-t- of Six Types of Reinforced Concrete 

Fence Posts 3*6 

Trade Notices J, 43°i 54-, 59 6 

Tramway Sleepers, Concrete n-\ 373 

University >f London 53 s 

Vats for Olive Oil, Concrete 053 

Vaults, Ccncrete 59 

Warrington Bridge -64 

Westminster Technical Institute 538 

White City, The 264 

Zeppolin Raid-, Police Warning 538 

NEW WORKS: 

Bridge at Allentown 

Bridge o\er the River Calder at Sterne 
Mill>, near Sowerby Bridge, Halifax, 
Yorks, Reinforced Concrete 

Bridge, C'acton-on-Sea, Ornamental Rein- 
forced Concrete 

Bridges, Coventry Loop Line, London and 
North-Western Railway, Reinforced Con- 
crete 

Buildings in China, Reinforced Concrete ... 

Church Hating-, Xew Zealand, Reinforced 
Concrete 

Cleckheaton Gas 

Column Eridge 
The Concrete 

Concrete Cottages at Norwich, Some 

Cottages at Wrothnm, Concrete 

Electrification of the London and South- 
western Railway (Suburban Lines), Rein- 
forced Concrete in the ... 

Gallery at the Empire Theatre, Whitby, 
Description of Reinforced Concrete 

Indo-Chlna Bank, Singapore, New Offices 
for the 

Larex- Concrete Arch Culvert, A 

Ma--achu-etts Institute of Technology, 
The Xew Building: 

N v Offices for the Indo-China Bank, 
S'ngapore 

New York State Barge Canal, Concrete and 
Electric Work on 

Park^\ : !le Concrete Dam and Power Plant 

Suh-tructure of the Lethbridge Viaduct, 
Canada 

Wigan Baths, Millgate, Extension and 
Alterations of the ... 

POPULAR USES : 

Concrete Po^ts for Letter Boxes in U.S.A. 

Concrete Troughs, Some 

Sanitary Floors for the Dairy Barn 

RECENT VIEWS : 

Application of Concrete in Modern Sani- 
tation, The. Bv Henry J. Tingle, 
M.Inst C.E. ... ' 

Arch Calculation, Some Modern Methods of 

Construction and Protection of Buildings 
in Relation to lire, The. By A. Alban 
H. Scott 

Concreting in Freezing Weather and the 
I of Frost upon Concrete. By J. 
Eiatnmersley-Hcenan, A.M. Inst. C.E. 

Concrete Lined Reservoirs for Oil 

Economy in Reinforced Concrete Construc- 
tion By 'I A Watson, AM [nst.C.E.... 
Fire Protection of Structural Members. By 
S. Broadbent 

Institution .: Civil Engim ei 

Lime Concrete in the East. By E. A W. 
Philips, M.Inst.C I 

London Building Ait- with somi Sugg* 
Amendments. Th< By born C. Hills... 

Parabolic Reinforced Concrete Arch. By 

A M Henderson and A. E. Snape 
I'ile Holder Foundation, A Com 

Franc i- E. I >rake 

Point, n pecting Reinforced Concrete 
Road-, Sewerage, etc. By Arthur 

I llins, M.Ii • ' 1 

1' rtland Cement Concrete I' - eiuenl for 



53 
419 

3°4 

368 
103 

37- 
365 

212 
644 
254 

583 
253 

420 

475 

159 
420 

528 
50 

641 
473 



313 
109 

55 



95 
151 



By 

for 
I. 



Country Road By Charles 11 Moon 

fil !<1 and Jam' I V . hel 1 

Pi idential Addn , In titution of Civil 

liriL' ; n< ' r 

Protection of Ancient Buildings, The. 
By W. A. Forsyth, E R I B \ 



153 

47 
578 

207 

49 
640 

412 
»97 

5 -5 
409 

523 
640 



a and Problem- arising therefrom. 
By 11. Kempton Dyson ... 

Sonic Modern Method- of Arch Calcula- 
tion. By Ewart S. Andrew-, B.Sc. 

Stability of Quay Walls on Earth 
Foundations. By F. E. Wentworth- 
Sheilds, M.Inst. C.E 

Tests of Reinforced Concrete Structures 
on the Great Central Railway. By J. 
Benjamin Ball, M.Tnst.C.E. ... ' 

Wind Pressure, Some Notes on. By R. 
Graham Keevil, A.M.I.Mech.E 



REINFORCED CONCRETE : 

Bridge over River Calder 



Reinforced 



over 
Concrete 
Bridge at Clacton-on-Sea, Ornamental Rein- 
forced Concrete 
Bridges on the Columbia Highway, U.S.A., 

Some Concrete 
Bridges. Coventry Loop Line, L. and 

N.W Ry., Reinforced Concrete 

Bridge near Merthyr 

Bristol General Hospital, Reinforced Con- 
crete at the ... 
Buildings in China, Reinforced Concrete... 
Caissons at Sunderland Docks, Reinforced 

Concrete 
Church, Hastings, N.Z., Reinforced Con- 
crete 

Cleckheaton Gas Works 

Contractors and Reinforced Concrete 
Crossley Lads' Club, Manchester, Rein- 
forced Concrete at the ... 
Earthquake Districts, Reinforced Concrete 

in ... 237 

Economy in Reinforced Concrete Construc- 
tion ... ... ... ... ... ... 207, 

Effect of Reinforced Concrete upon Archi- 
tectural Design 
Electrification of the London and South- 
western Railway (Suburban Lines), 
Reinforced Concrete in the ... 
Engineering Society of China, The Report 
of the Special Committee on Reinforced 
Concrete 
Ford Motor Co., Chicago, A Reinforced 

Concrete Building for the 
Eixing Temporary Blinds to Reinforced 

Concrete Beams 

Gallery at the Empire Theatre, Whitby. 

Description of Reinforced Concrete 
Lightning on a Steel Dome and Reinforced 

Concrete Walls, An Instance of 
London County Council Regulations for 
Reinforced Concrete Construction 

377. 44i. 5°2, 
Massachusetts Institute of Technology, 

The New Building 

Moment of Inertia of Reinforced Con-crete 

Sections 

Municipal Works, Concrete and Reinforced 

Concrete in ... 
New Exchange Buildings, Swansea, The ... 
New Gas Works at Keilehaven, Rotterdam, 

Reinforced Concrete in the ... 
Padstow Station, Reinforced Concrete 
Parabolic Reinforced Concrete Arch ... 
Pier at Padstow, Reinforced Concrete 
Plain and Reinforced Concrete Arches 
Points respecting Reinforced Concrete for 

Road-, Sewerage, etc. ... 
Port Dun das Distillery 
Power House, New Zealand, Reinforced 

Corn rett 

Southampton, Reinforced Con- 



Stand, Cheltenham, Reinforced 



Quay Wall 

■ rete 
Rat ' ' ourse 

('oner' (r 

Reinforced Concrete Construction 
Reinforced Concrete in Practice 
Sheet Piling, A New Method of Reinforced 
< !on< rct< 

Standard Specification for Reinforced Con 

Crete Work, A 

1' t- of Reinforced Concrete Structures on 

the Great Central Railway ... 
Wharf and Jetty for the Port Talbot Rail 
way and Dock Co., New Reinforced 

( Oil' I ' f ' 

Wigan Baths, Millgate, Extensions and 

Alterations of tie 



43- 
151 

35* 

4& 
246 

410 

3°4 

404 

368- 
323 

169= 

it>3 

63 

372 
36S 
321 

483 

62 

167 

433 

583 

54 

77 

522 

253 

83- 

567 
159 
179. 

61 

117 

337 
565 
525 
223 
424 

523 
381 

>7 

233 

3 

49 

3<>8 

3'° 

122 

46 

6ol 

473 



Digitized by the Internet Archive 

in 2010 with funding from 

University of Toronto 



http://www.archive.org/details/concreteconstruc10lond 



' CONCRETE, 

AND 

CDNOTRUCITGNAL ENGINEERING 



Volume X., No. l. London, January, L915, 

EDITORIAL NOTES. 



1915. 

1 1 is useless to ignore ilu fact thai concrete and reinforced concrete have, 
during the nasi year, been somewhat " marking 1 time," and for all concerned 
ii would be well to understand this plainly with a view to finding some remedy. 
I he primary cause goes back some two or three years, when a tendency 
to exaggerate the utility of these materials, both from the practical point ol 
view and that of economy, brought about a certain reaction, and by the very 
strenuous efforts of the steel frame propagandists, who were only too pleased to 
foster any feeling of disappointment. 

The professional man and also the leaders of the industries concerned only 
too keenly resent exaggerated claims, as the true claims are sufficiently 
wide and proved by experience. 

L nfortunately the Concrete Institute, which was intended to do so much 
for concrete and reinforced concrete, and started doing it so well, has not been 
able to P"ive to the true advancement of the subject that undivided and strenuous 
attention which had been anticipated. 

What with the bickerings within the Institute on matters of manage- 
ment and administration, what with the energetic set made by the steel 
frame interests to obtain control of the Institute and the desire of certain of 
the members for special prerogatives, the principal objects of the Institute were 
at times almost entirely lost sig"ht of, and had it not been for the outbreak of 
war, whereby all contentious questions were shelved, the year 1914 might easily 
have seen the disbandir.ent of the Concrete Institute or its departure into other 
realms to make way lor some new and more virile institution. 

What we require at the present moment to wipe away the stagnation 
which has made itself felt in matters relating to concrete and reinforced con- 
crete is, on the professional side, an active indication, provable by facts, of the 
good work done and the economies effected and advantages obtained by 
concrete and reinforced concrete in the past decade. The fine work accom- 
plished requires description; examples of success, honest analysis; interesting 
facts, full as distinct from secretive explanation ; rather than any more 
arguments as to various mathematical conundrums, algebraical notation, and 
possible regulations in connection with this subject. The whole of the subject 
has so many practical elements and interests that it will appeal to all con- 
cerned more readily if examples are more actively put forward, discussed, 
analysed, and urged as useful precedents. 

On the industrial side the same holds good, and we want more actual 
facts as to what has been done and what economies have been so splendidly 

6 i 



1915. [CONCRETE) 

effected rather than dicta oJ the "might-have-beens" or future possibilities. 
Those concerned on the industrial sick- should plainly lace the fact that there 

main limitations to Concrete and reinforced concrete, just as there are for 
any other form of construction. 

Bui if we have spoken to the professional man and the industrial leader, 
there are other classes to whom we would also like to say a word. 

The first are the makers of all those forms of machinery so useful in 
concrete work". Be it the maker of the block-making machine or the concrete 
mixer or what not, ii lies in his hands, too, to be more precise in indicating by 
examples what his machines have achieved, rather than to make statements 
as to the achi< vements and output he anticipates. He should simplify his 
literature, and even limit the number of types of appliances he puts on the 
market so as not to confuse users, and, above all, he should remember that in 
times like the present he can not only assist materially in the use of concrete and 
reinforced concrete at home, but particularly in India and in the Colonies, in the 
South American Republics, and elsewhere, thereby indirectly not only benefiting 
himself, but also the professions and trades of the home country. 

Lastly, we would speak to the purveyors of the materials of which 
concrete is composed. There is little we can say about the great cement 
industry of this country as far as improvement in policy is concerned. It 
fortunately happens to be one of those industries that is conducted on 
thoroughly national, we may even say international lines, and the splendid 
advancement of the product of Portland cement has been the greatest auxiliary 
in the development o! concrete and reinforced concrete during the past decade. 
This industry, too, can be trusted to hold its own at home, in the Colonies, and 
abroad. Its work has been a credit to our manufacturing activities. 

Hut there are various purveyors : those who provide stone, sand, 
clinker, coke breeze, etc., materials which all play a part in the production 
ol concrete and reinforced concrete. These have not as yet quite lived up to 
modern requirements as a whole, although there are one or two notable 
exceptions, and the same must be said ot those local purveyors in many ol 
our Colonies. The makers of bars and mesh work can likewise, with perhaps 
one or two notable exceptions, work on broader lines. It is almost scandalous 
that professional men and leaders in the industry should be constantly handi- 
capped by unsatisfactory deliveries of the materials known as aggregates, and 
so often have to encounter delays from the bar and mesh makers. 

Generally speaking, all concerned in concrete and reinforced concrete — the 
architect, the engineer, the quantity surveyor, the specialist designer, the 
specialist contractor, the ordinary contractor, and the purveyor — should realise 
thai the;, are concerned in one of the greatest constructional developments that 
have been seen during the last 50 years; that between them they have the 
making ol one ol the greatest industries within sight at the present moment, 
and that the time has arrived for more active co-operation between all the 

interests concerned and for a fixed policy as to development at home, in the 
Colonies, and certain foreicn markets. 



j.CONSTBUCT ion u 1 



REINFORCED CONCRETE RACE-COURSE STAND, 




REINFORCED CONCRETE 






RACECOURSE STAND, 
CHELTENHAM. 



By ALBERT LAKEMAN, MSA. 

We have already shoivn in previous issues that reinforced concrete is ivell suited and 
has many advantages to structures such as the one here described, and the present example 
shoivs that the material also lends itself ivell to architectural treatment vlhen used in this 
connection. —ED. 



This race-course stand is an excellent example of an architectural reinforced 
concrete structure, and indicates what can he accomplished when the work 
is designed by architects who are in sympathy with the material and who take 
advantage ol the possibilities which it lends to simple, pleasing lines expressive 
o\ the constructional value of the material employed. The finished stand is 
illustrated in our frontispiece, and it is undoubtedly one of the most pleasing 




Fig. 1. View of Balcony on First Floor, 
Reinforced Concrete Race-Coirse Stand, Cheltenham. 

stands in this country, and was completed about twelve months ago. The 
architects were Messrs. Chatters and Smithson, F.R.I. B.A., of Cheltenham, 
and the contractors for the whole of the structural work were Messrs. 
William Moss and Sons, Ltd., of Loughborough, while the details of 
the reinforced concrete work were prepared by Mr. H. M. de Coleville, 
A..R.I.B.A., ol 48, Bedford Row, London, W.C., to suit the require- 
ments of the architects. The stand is rather unique in the fact that the 



ALBERT LAKEMAX. 



[CONCRETE 



topmost tier is arranged in such a manner that spectators ran obtain a view of 
the racing from both back and front of the stand, this being brought about by 
the position of the building in relation to the race-course, the latter curving 

away to the rear of the structure with a wide sweep. 

The stand has a total length of go ft. and a width of 44 ft., and the ground 
floor is arranged as a large court with an open front and enclosed on three 
sides only. Two large open fireplaces are placed back to back in the centre 
of the court, and a wide staircase leads up to the upper part of the stand, while 
access is obtained from the club enclosure to the paddock through an entrance 
at the back of the court. On the first floor a large luncheon room is provided, 

u ... . t-K-r: 



*"' T" T"* t .^Vt^ T? "'.-.- I '* 1 




ELU<af,.n -CD 

Viti. 2. Cross-Section showing Braces 
Keiniorckd Concrktk Rack-Course Stand, Chkltknham. 



this being 40 ft. long and 23 It. wide, finished with a barrel ceiling executed 
in fibrous plaster with suitable enrichments. An ingle-nook is formed at one 
end of the room, and the walls and columns are treated with panelled and 
fluted wainscoting. A view of the race-course and paddock can be obtained 
from the balconies, which are arranged on either side oi this room, which is 

provided for the use of the committee and stewards. The remainder ol the 

first floor is allocated to private luncheon rooms, with the necessary offices for 
Service, boxes, and balcon'es. 

The constructional work was carefully planned and detailed to suit the 
architectural treatment of the stand, and the columns were spaced at about 



/gaggBBCTBH SH REINFORCED CONCRETE RA( i I WRSE STAND 

KilN(.IMll-'lN(.H 




c 

8 w 

OS H 

o X 

1 U 

a w 

2 u 
ii < 

e ^ 

o • 

V H 

W 

a: 

rn ~ 

. z 

■CC 

'■Z o 



i j-i i . i 'Hi res, both Longitudinall) 
and transversely, thus giving si 
main 1< tngitudinal i <>\\ s and foui 
transverse rows. One end <>l i In 
stand is, however, somewhat 
irregular in outline owing to some 
projecting portions, and the spacin 
t>l the columns u.is modified as 
necessary to suit these projections. 
In addition to the vertical support- 
ing columns several diagonal struts 
;n braces were introduced in order 
to stiffen the structure and render 
ii perfectly rigid and free from 
vibration, and ;i section of the stand 
showing the constructional mem- 
bers is illustrated in Fig. j, where 
several of the braces can be seen. 
It might appear al first sighl that 
these would be detrimental to the 
stand from a spectator's point of 
view, but the}- were all carefully 
considered as regards the positions, 
and in every case- they arc arranged 
to come within the partitions or in 
such a position that the) do not 
interfere either with the view or the 
decorative treatment. The effective 
bracing of a structure of this kind is 
undoubtedly of great importance, 
owing to the exposed position and 
the nature of the load, and this 
has been fully considered by the 
designer. 

The foundations to the columns 
and braces are carried down to a 
level 4 ft. below the ground line, 
and in some cases the two are 
combined below the ground level to 
come upon one foundation slab, and 
in other instances they are separate. 
In the drawing reproduced in Fig. 
4 an example is given of the com- 
bination of columns and braces, and 
also a plain column foundation. 
The latter are generally 4 ft. 
square, the largest employed being 

5 



ALBERT LAKEMAN. 



[CQNCBETD 



4 ft. 6 in. square, and these have a minimum thickness of <.) in. at the extreme 
outer edges, increased by sloping up the concrete towards the column to give 
a maximum of 12, 15, or 18 in. according to the load. In addition to the 
increase in thickness obtained by sloping up the concrete, the intersect ion 
between the column shaft and the base is covered with a block of concrete 
usually K) in. square and about 18 in. high, an example of which is shown in 
the detail above referred to. The reinforcement in these slabs was composed 
ol a lattice ot f-in. and f-in. rods in the lower surface, having a cover of 2 in. 



is-3i« 







Column 5 5-fe< •Vt>V«,a« \nt^ 

— ^Fr^ 



Column K 4 0-40 
C.U-.-C 



Coluw<\ Jq, l»<< 



it «. 




I I ! 



: 




£^=^t 



1 ; 



^j 




Fig. 1. Showing Foundations to Columns and Braces. 
Reiki or< ed Concrete Ka< e-Course Stand, Cheltenham. 

pf concrete, these rods being Spaced at 4-in. Or 6-in. centres. When the 
foundation to the brace occurred close to the column slab it was combined with 
it, as shown in the drawings, by forming a canted slab, pari of which was 
horizontal \\w<U-i- the column and the other pari placed at righl angles to the 
length ol the brace to transmil the thrust directly to the soil. 

All the columns up to the first floor are n in. square, and above this they 
are reduced to 10 in. square. They are all reinforced with four lines of vertical 
reinforcement, consisting of |-in. diameter rods above the firsl floor, and 

6 



( &EwiNh"HN?^ REINFORCED CONCRETE RACE I 01 RSE STAND 

cither ,-in. diameter rods in Moss bars below this level, th< lattej In in- placed 
with their webs on the diagonal lines joining the opposite corners. I ) i < whole 
ol the vertical rods are tied with Ar-in. diamctei links a! 9-in. and 12-in. ccni 

J 



^~" 1 ' && " * — "' w " m 



■ - £ 5! ■ '" '..'■ ■•' -- 



;,,> ... ;i _..j @: 






4e 



t$p« 



■\". 



ii 






v, 



~- 



i • 



iu 



■jji. *i5s 



V 












— ®* i;-- ^® 



, 111 — »!.* < . ■ ... ifl 



« 



i 



5t...l>»« k*fiax 



U*---:--®- 






"®g M ': ^ <fo~ 



^ k - 



& 



l! • 



— H- 



» 



* 



|l 






ja 



■^m 



:"-_-^ft - z---.! c r -— z^r-- _ --.^ t ".- $«. 



.^c. 



--1^-y^:-^-:~C:-::^: 



>-t 



9 



:i&M.-.z.zz4. 



'..— 1 



Fig. 5. Second Floor Plan. 




Fig. 6. Section of First Floor Balcony. 
Reinforced Concrete Race-Course Stand, Cheltenham. 



The braces arc all 12 in. by 8 in., reinforced with four main rods tied with links 
at 12-in. centres. The total height of the stand from the ground level is about 



ALBERT LAKEMAN. [CONCRETE ) 

55 ft., and the braces arc arranged in two heights in some positions. The main 
beams at the first floor level have a maximum span of 14 ft., and these vary in 
size considerably, the largest being 18 in. deep and 10 in. wide, reinforced with 
two Moss bars and having stirrups throughout the length. 

The floor is divided up into bays, about 14 ft. square, by these main beams, 
and generally one secondary beam is introduced into each bay to cut up the 
span for the floor slab into 7 ft., and these secondary beams are generally 14 in. 
deep and 8 in. wide, reinforced with one bar in the lower surface; and stirrups 
as for the main beams. 

The slabs are 4 in. thick, and they are reinforced with !-in. rods at 8-in. 
pitch, and |-in. diameter continuity rods are plaeed in the upper surface where 
passing over the beams. 

The front balcony is reached from the first floor level by two steps of gin. 
each, and as the level of the balcony is thus 18 in. below the main floor level, the 
main beams carrying the adjoining- bay had to be somewhat varied to suit the 
levels of the steps. The beams are 8 in. wide, and they are constructed with a 
raking soffite and a varying depth, and they are reinforced with three bars 
in the lower surface. The balcony itself has a projection of 2 ft. 8 in. from the 
centre line of the outer row of columns to the outside face of the balustrade, and 
the floor is formed with concrete, 4 in. thick, reinforced with ^-in. diameter rods. 

The floor is carried by cantilevers placed at each column, these being 8 in. 
wide and having- a maximum depth of 25 in., 12 in. of which occurs under the 
balcony floor and is visible in the finished work as a bracket. These cantilevers 
are reinforced with two |-in. diameter rods, which are carried along the top of 
the member and continued down and around to the underside and back to the 
supporting column. Ties, rV-in. diameter, are passed right round the rods 
between the two surfaces, and the rods at the top are cranked down into the 
adjoining main beam. 

The parapet to the balcony is of reinforced concrete, 3 ft. high and 4 in. 
thick, with small projecting piers over each cantilever, 10 in. wide and 2 in. 
projection. The parapet is reinforced with A-in. vertical rods at r4-in. centres, 
these being benl at right angles at the bottom and carried back in the floor 
behind the columns, and three horizontal distribution rods are also provided, 
these being lapped over the cantilevers. The parapet is finished at the top with 
a moulded concrete capping, 8 in. wide and 3 in. deep. A detail of this work 
is illustrated in "Fig. o. 

A back balcony, 5 It. 6 ill. wide, was also provided, but no cantilevers were 
required for this, as it is directly carried by 12-in. by 8-in. beams supported 
"ii ili* columns, the outer row of the latter finishing at this level and supporting 
the beams under the miter edge of the balcony. The floor of tin- balcony is 
4 in. thick and reinforced with .-,-in. diameter rods at 10-in. centres. A front 
balconj is also provided at the second floor level, which is about 24 ft. 6 in. 
Iroin tin ground, and this is constructed in a similar manner to thai occurring 
al the first floor. 

I he second floor comprises the rool stand, where provision is made lor a 
view from ironi and back, as previously mentioned. 

Ike accommodation for spectators in tbc froril consists of twelve tiers, 

each 18 in. wide and willi a rise of 6 in., and a level walking wav, } ft. wide, 



&e^tSeringS REINFORCED CONCRETE RA( ursb stand 

is formed half-waj up the height and immediatel) over ihe second row oi 
columns. At the top of these tiers a level platform, 7 ft. wide, structed 

before descending at the back, where there are four tiers 18 in. \\id< and \i it 
high, ; 1 n<l 1 wo platforms, each 3 ft. wide. The front tiers are constructed with 
a minimum thickness in the soffite oi 1 in., and litis is reinforced with '-in. and 
i-in. rods parallel to the pitch, and with continuit) rods when passing ovei 
the secondary beams. The latter are formed under the edges <>l the int< 
mediate walking"-\vays or platforms, and also in the centre >>l the length 
of the tiers, and they are carried by the main beams or the columns 
direct. The back tiers are constructed on ;i different principle owing to the 
greater depth of the risers, these being each designed as a beam, with a 
thickness of 5 in. and being reinforced with one bar in the lower surface, while 
the treads are \\ in. thick with |— in. rods at u-in. centres on the underside. 
The main beams, which occur at each line <>l columns, are varied considerabl) 
according to their positions; in some cases they arc sloping and parallel to 
the pitch of the tiers, and in ether cases they have a horizontal soffite and a 
varying depth caused by the rise and I all oi the roof. Reinforced concrete 
parapets are constructed all round the roof, thai on the front being supported 
by the balcony cantilevers and that at the back occurring over the outer line 
of beams, with the columns carried up to the top of the parapet to form pro- 
jecting piers on the face of the wall and divide it up into panels. All these 
parapets an 1 similar in construction to that illustrated in the detail of the first 
floor front balcony, and the finished effect can be seen in the exterior view ol 
the stand. 

This structure forms another excellent example of the applicability of rein- 
forced concrete construction, and its value for this class of building is becoming 
more popular day by day. The questions oi maintenance and safety against 
fire are of primary importance, and this material is ideal from these two stand- 
points, while the initial outlay required will always compare favourably with 
any other material which possesses the same strength and lasting properties. 




Fig. 7. Dining Room. 
Rkinforckd Conxrkte Race-Course Stand. Cheltenham. 



EWART S. AXDRHWS. 



[CONCRETE! 




1 



PROBLEMS IN THE THEORY 
OF CONSTRUCTION. 

COLUMN BENDING MOMENTS 
IN FRAME CONSTRUCTION. 



By EWART S. ANDREWS, B.Sc.Eng. (Lond.), M.C.I. 

The folloiving article ivill probably be of interest to all designing reinforcea 

concrete ivork. — ED. 



< >NE of the most difficult problems in the theory of construction is that of the bending 
moments transmitted to columns in frame construction in which, as in steel frame 
construction, the beams are firmly connected to the columns to secure rigidity, or, in 
reinforced concrete construction, the whole structure is monolithic. 

Most designers have now realised that in reinforced concrete design you must 
allow for the reverse bending moments due to the continuity or fixity of the beams 
at supports, but comparatively few have realised the very important fact that bending 
moments are transmitted to the columns, and that such bending moments must be 
allowed for in scientific design. The great need in this matter at the present moment 
is the discovery of a method which will be sufficiently near to the results of sound 
theory, and yet will be sufficiently simple for practical designers to be able to adopt it. 
Messrs. Faber & Bowie have given an excellent treatment of the subject in their 
'" Reinforced Concrete Design " (Arnold). Our experience, however, is that, thorough 
though that treatment be, it involves a mathematical treatment which many designers 
cannot follow. The aim of the present article is to explain from the standpoint of 
graphics the principal points involved in the problem, to assist in the following of the 
more advanced treatment, so that all designers may, if so disposed, study the question 
of these bending moments, which all the leading authorities of structural theory regard 
a- of fundamental importance. It is a common source of complaint among practical 
designers that the exponents of theory indulge in advanced mathematics instead of 
common sense and the results of tests. The reply is that common sense is a very 
variable quantity; the history of scientific progress shows that common sense is usually 
common fallacy ; Galileo was tortured for saying that the earth was round, whereas 
common sense said that it was fiat. As to tests, nobody values them more than the 
mathematical section of engineers, and nobody knows more clearly than they the great 
expense and extreme difficulty in getting satisfactory results from tests. Satisfactory 
te -ts require the very besl brains and plenty of apparatus, both of which are costly. 

Relation between Slope of Columns and Bending Moments. 

The bending moments are induced in the columns by the fact that the beams 
slope slightly under the deflection cau c ed by the loads, and must transmit such slope 
and deflection to the columns. The columns thus ad in part as vertical beams, 
and the relation between the Blope, d< flection and bending moment is given by " Mohr's 
Theorem," which we will state as follows : — 
10 



G 



<i t,MilNKtl<IMi — 



PROBLEMS IN THE THEORY OF CONSTRUCTION, 



By treating the betiding moment diagram oj a beam oj constant ■<■//. n 
imaginary load, and drawing tin- shear .///</ B.M, diagrams, th( sheat diagram 
gives the slope of the beam <///</ the B.M. diagram the deflection, each multiplied by 
El i E Young's Modulus ; I Mament oj Inertia oj Beam Section). 

["he slope of a beam is the tangent of th«' angle of Inclination with it orig 

/>_,!_ o direction, and foi the very small angles with 

, gj g T" ft which we are concerned the taneenl ii equal to 

the angle measured iii radians. 

We will now take a column I) /•„". which is 
forced to have a slope * at one end. and < on idi i 
the bending moments resulting from foul 
possible methods of suppoii of the othei I nd. 

Case /. Other end fixed vertically. A 
shown in Fig. 1. the end 1) is given a -lope 
and the lower end is fixed vertically; this would 
happen if the lower floor was equally loaded on 
each side of the column, but the; upper floor 
was loaded on the left-hand side only. In all 
the figures the slope is shown exaggerated for 
clearness. There is a B.M. = Bd at I) and a 
B.M. = B£ at /: ; these two B.M.'s arc opposite 
in sign because the curvature of the beam is in 
the opposite direction at the two ends. Since 
there is no transverse load between /) and /;. 
the B.M. diagram will be a straight line between 
the two points: we thus get the B.M. diagram 
d b a c. We now want to find the slope & at J) 
in terms of the B.M.*s. 

The slope at the ends will be given by the 
imaginary reactions there, since the imaginary 
shears at the ends are equal to the reactions. To simplify our calculations draw a c 
parallel to c d : then we may regard the B.M. diagram as made up of the rectangle 
accd, minus the triangle a be. The imaginary load, therefore, consists of the 
triangle, whose area P, acts at its centroid in one direction, and the rectangle, whose 
area P., acts at its centre in the other direction. Let r e = imaginary reaction at e. Then 
taking moments about d in the usual way we have : — 




Fig. 1. 



r< 



h = I\. --P, 

■ 2 



= B E h.--- (B D 

o o 



B E )h 



r.. 



= - 1.3 B E - {B d -\-Be) 

6 ( 

= lr (sBe-B d -Be) 

= h - (2 Be ~ B d 
6 \ 

= \ (2 B E - B D 
6 \ 



(D 



But by Mohr's theorem r c = EI$, if I c is the moment of inertia of the column 
at E and = 



1 1 



EWART S. ANDREWS. 



[CONCRETE] 




but r d = EI t 6 



i.e. P>» = 



Fig. j. 



4EI C B 



J i (4a) 

D 2EI V 6 

lip 

// (4b) 

If. therefore, the angle 6 is known the value 
of Ii{) can be calculated. 

Case -'. Other cud hinged. -The 
condition that the end E is hinged imposes 
the restrictioD thai the B.M. is *ero there. 
We thus gel the B.M. diagram in the form 
ol the triangle d c b shown in Fig. 1. the 
are;i /' acting through tin- centroid at a 



distance 



from the top. By taking 



moments about <l we have 
r,Xh V 

Hn.h . 2h 

1 



Hn.h 



i.e.. 



/: , 



h 



.-. = " (2B E -B D ) 
6 

Le.,B„=2B E (2) 

Therefore d the point of contraflexure 

occurs at from the bottom. 
3 

Now rind r d by taking moments about e. 

T1 , D h P v 2h 

Then r t , . Ii = P., • -— — — 

' 2 3 
=-B,:.h. /l r ]</h>+Ih:)h.: 2 j 

= %\m E -2 <B D +B E ) | 

6 ( > 



6 < 



B* -2«« 



r,f 



4 2 -!^-2B4from(2) 

6 < 2 ) 

/r 
6 
Ir. Bd 

4 

/i • B n 



■(-*%*) 



4 



(3) 




/■^p 



. 



A 



5) 



Fio. ■ 



I 2 



j.lONMk'UlTIONAi: 
« 1 r-JdlNl l.K'INti — 



PROBLEMS IN Till-: THEORY OF CONSTRUCTION, 



Now i ,, ■ i , /' 

Boh 

B D .h 



i , 



/;, // 



6 



l 



I a 

.'. Slope at /:' slope at /) 

F 2 ' 2 

Case 3. Other end slopes equally in OPPOSITE direction. — This occurs il th< 
upper floor is loaded on the left of the column and the lower floor equally loaded 
in the right. In this case the B.M.'s at the two ends must be equal, since; the slopes 
are equal and the curvature is in the sam2 direction. Ths B.M. diagram will be a 
rectangle, as shown, and the column will bend to a circular arc. 

P__ BpJi 

.'. each imaginary reaction = ~ — ~ 



E.I C .6 = B D . 



i.e. 



Bn— B E 



2E.L..0 



(7) 



Case /. OtJicr end slopes equally in 
same direction. — This case is shown in 
Fig. 4. It would occur if both floors were 
loaded on left-hand side only. 

The slopes at the two ends are the same, 
so that the B.M.'s will be the same; the 
curvatures are in opposite directions so that 
the B.M.'s will be opposite in sign. 

Taking moments about e we have 
5// P.h ZP.li 



>'</ 



h=P 



i.e. 





6 


6 




3 


r,i 


_2P_, 1 
~3 -*•' 

_B D .h 
6 


B D . 

2 


Ji 




516 


= B n .h 
6 








B D 


_ 6E . I c 6 










Fig 4 



(9) 



Case 1 
Case 2 
Case 3 
Case 4 



Summary of Results. 
R _4El c 6 



Bn = 



B D = 



li 
2EI C 6 

h 
hEI c 



h 



EWAkT S. AS'DRBWS. 



{CdNCHETE) 



We learn from these four results the very important fact that the less the 
deflection of column for a given end slope the greater will be the B.M. and therefore 
the stress, because it is clear that the deflections will be the greatest in Fig. 3, next in 
Fig. 2. next in Fig. 1. and least in Fig. 4. 

Calculation of Slopes. 
In a rigid analysis of these problems we should take account of the fact that the 
rigidity of the columns themselves will affect the slopes which the beams will have, but 
an allowance for this causes great mathematical complications, except in the simplest 
cases. We will fc 1 ow Messrs. Faber and Bowie in neglecting this as a first approxi- 
mation in some cases; the result will err on the right side, but, as we shall show later, 
the error will often be considerable unless the beams are very rigid compared with the 
columns. We will first consider the case of a single span uniformly loaded and carried 
on columns at the ends. The B.M. diagram for the beam is a parabola as shown in 
5. W being the uniform load per unit length. 

1 

2 

= 1 2 

2 ' 3 

= wF 

24 

If E is the same for beam and column and Is is the moment of inertia of the beam, 

zvj 
24 
. w? 
24/b 



Then r = - area parabola 
, wl 2 



E.I B . 

i.e., E 



10) 




For columns fixed at the ends 
(as in Fig. 1) we have, putting 
this value in (4<7), 

wF 



h 24//, 
~~ 6 ' h ' In 



Bn for Case 1 



12a; 



(11) 

Now let — -5- c be called the 
/ h 

stiffness co-efficient and be 

given the letter 8, 

ivF 

6s 

Similarly we should get 

wl 2 

8s 

wl- 

1 2s 

XV I' 

4s 

Now let the compressive stress 
due to beading in the column 
be Cb and let //< be the distance 
from the neutral axis of the 

column to the point where the > required'. We will work out our results for the 

fixed ends of the column. 
•4 



Case 2 


B D 


it < 

" 8s 


(12b) 


Case 3 


B D 


wl' 

1 2s 


(12c) 


Case 4 


B D 


_wF 
~4s 


(12d) 



I, OON> rpni-noN A 1.1 

AKM.INt.H-'INd —J 



PROBLEMS IN THE THEORY OF CONSTRUCTION. 



We then bave 



o, 



/>'/ .11, 
I, 

xc.r /, / 

(> hi 



A grain it' the beam is designed for a B.M. of 



wl* 



1 ; 



and the working stress in the 



beam is s, and the distance from the neutral a.\i> to the point where it- ;tn 
taken is //,,. we then bave 



(14) 



w> 



n c l 

h . I B 



1 15 



8 // /; 

. s.f i: 

75 ///; 
s . ;/. / 
' /D II a. Il 

Corresponding results will 
be obtained for the other 
cases. As we have ex- 
plained already, this for- 
mula must be used only 
in the case in which the 
column is relatively very 
slight compared with the 
beam. 



Effect of the Stiffness of 
the Column. 

In the present case 
of a single span with a 
uniform load we can allow 
for the effect of the stiff- 
ness of the column in the 
following manner. The 
B.M. at the tops of the 
columns will act as reverse 
B.M.'s on the beam, thus 
producing the B.M. diagram shown in the battom of Fig. 5. 



CD 

-a 

c 

LU 



u 



OS 


















' 




'OS 


. 










































■07' 










































'Ob 






















J \ \ 


















'05 






\ 


















\N 


















\ N 


Cot 


Umns 


fixed 


















^^ 








: 


C3 






Co'o< 


mns h 


in^&A 








: 




































|""*""---l-— 






















Of 


































1 


O 
























1 




} 




5 


1 


l 


5 



Stiffcess Coefft. =d . 



Fie. 6. 



We thus get 



r = % area of parabola— £ area of rectangle 



24 2 



Ei B .e= 
:.E6= 



24 
24 I B 



B D 



I 



2 
BpA 

11 n 



(16) 



For fixed lower end of the column, therefore (using equation 4), we have 

o _4/ c / wl B D .l\ 

I c l _ 2B».I c l 
I. Id //•//; 



' 6 s 



2 Jin 
s 



EWART S. ANDREWS. (CONCRET E! 



6 s 

r i> 



6 .(.+g 

6(s + 2) 
By similar reasoning for the other cases we get the following summary of results, 
which the student should check for himself : — 

Bd= 6W) (17a) 

Case 2 B "=W^T) 07b) 

Case 3 B B = { ^ ) (17c) 

S; =4lSl) (17<1) 

If we call Ih) — — — where k is a constant given in the summary of results on p. 13, 
h 

our result may be expressed in a general expression as follows : — 

I-rom equation (16) hu — —-——— 

2Mb 2 In 

hB n __ wl 2 Bo. I 



kl c 2Mb 21b 






B^ _wl 2 II c 


/>'n 


7. /,. 


k 24 h . I B 


2 


//.//; 


_wt 2 B n 






24 ; 2s 






\k 2s) 24s 






B n {2s + k)_^wl 2 






Iks 24s 













12(2a+*) (17) 

Fig. ( > shows for various values of s the values of the co-efficients for the end B.M.'s 

in the beams which are the same as the B.M.'s at the tops of the columns in cases 1 

and 2. It will be noted that in each case if s = 0, i.e. the columns are infinitely stiff 

compared with the beam, B = *083 wl' (— ) this being the familiar value for a beam 

absolutely fixed at the ends. In using these curves, the resulting co-efficients are 
multiplied by wl* to give the B.M. The next case that we will consider is that of a 
continuous beam of two equal spans rigidly connected to three columns. 

< To be concluded.) 



16 



d 



nONSTUlKTlONAL 



REINFORCED CONOR ETE IN NHW Zl-'.ALANl). 




REINFORCED CONCRETE 
POWER HOUSE, 
NEW ZEALAND. 



By H. C. GAYFOKD, 
Public Works Department, New Zealand. 

The folloiving Notes on a Reinforced Concrete Building in Neii> Zealand, in connection 
ivith the New Zealand Government's Lake Coleridge Electric Power Plant, may te of 
interest. — ED. 

As an illustration of the use of reinforced concrete for building purposes where 
other materials are difficult to obtain, and as showing the favour with which it 
is regarded by engineers to the Government, the following brief description is 




View showing Building in course of construction. 
Reinforced Concrete Power House, Lake Coleridge, New Zealand. 

given of a power-house built entirely of reinforced concrete at Lake Coleridge 
in connection with the New Zealand Government's first hydro-electric power 
installation. 

The location of Lake Coleridge is about 70 miles west of Christchurch, and 
the current generated will be utilised to supply that city with power and light. 

c 1- 



H. C. GAYFORD. 



[QONCKEXD 




View showing Power House and Tail Race, with Pipe Line and Tunnel Outlet in background. 





Iff' 



>* 



i 




View ihowing Swit< hboard Gallery, Upper Gallery, and Reinforced Concrete Crane Runaway Beam. 
REINFORCED ( CRET1 POWER HOUSE, Lakk COLERIDGE, Nkw ZEALAND. 



1 8 



I': 



„(.r>NM AUCTION A I. 1 
i.EM(ilNhKWlN(i — u 



REINFORCED CONCRETE IN NEW ZEALAND. 



The power-house is situated on the banks «>l the Rakain River, [,200 ft. 
above sea level, and ;ilx>ui 2 miles from the Like. The only means <>'. 
!•> the site from the nearesl railwa) station al Coalgate, thirtj miles away, i 
1>\ road, pari <>l which was remetaJled 1>\ the Government to fai Ililate Iransil <>l 
materia] and machinery. 



r 




■ / 



Cross Section. 




\'ie\v looking down Pipe. 
Reinforced Concrete Power House, Lake Coleridge, New Zealand. 

All material for use in connection with the building- (with the exception of 
shingle and sand) was hauled from Coalgate to the site by traction eng-ines 
at a cost of 23s. per ton in addition to the cost of railage. This rendered it 
imperative to utilise local material obtainable on the site as far as possible. 
Sand and shingle were obtained from the river bed, where it was washed and 
screened before being carted to the site. 

C2 19 



H. C. GAY FORD. 



[(DNCEEXEJ 



The building, which is entirely of concrete, accommodates the whole of the 
generating plant, and covers an area of 13,500 sq. ft., its length being 180 ft., 

width 75 ft., and 
height from ground 
to parapet level 
35 n. 

For the rein- 
forced concrete a 
mixture of 1 part 
cement, 2 parts 
sand, and 4 parts 
shingle of f in. 
gauge was used. 
This mixture, when 
tested for com- 
pression on 4-in. 
a h cubes after one 
month gave an 
average of 2,400 
lb. per square inch. 
Concrete for 
machinery founda- 
tions and other 
dead loads was 
mixed in the pro- 
portions of 1 to z\ 
to 5, the shingle 
being screened to a 
2j-in. gauge. 

The steel for 
reinforcing was of 
& plain round section 
varying from J in. 
to i\ in. in dia- 
meter, and con- 
formed to the 
British standard 
specification f o r 
structural steel. 
When tested in the 
( rovernmenl 's labo- 
ratory in Welling- 
ton a tensile strength of 28 lens per square inch was determined. 

Aggregate for the concrete was obtained from the river bed, where it was 
wasted and screened. The method employed for washing was to Hume the 
shmgle (Kami a long wooden trough by means of water obtained from a creek 
at a higher level. 




20 



r • _ ooN^ry i ici ion a i } 

[A KT^.lNKFPlNt. — J 



REINFORCED CONCRETE IN NKW ZBALA 



The cemenl used throughout was oi \« w Zealand manufacture. 

A portable bath mixer was used, and was particularly adaptable to this 
building owing to the small quantity <>! concrete in the piers, which were spaced 
m er .i Large area. 

The building consists <>l piers spaced al 15-ft. oentres carried up to take 
the roof beams. These piers are connected ;ii a height <>l 21 ft. by a band ol 
concrete 2 ft. deep and 
[2 iu. thick extending 
round the entire build- 
ing. The lower portion 
between the piers to a 
lu ight o\ 8 ft. above 
lloor level is filled in 
with 9-in. curtain walls 
finished with moulded 
projections inside and 
out forming' the window- 
sills. 

The roof is graded 




1 to 35 to shallow 
g"utters formed in the 
concrete at the back of 
the parapet wall, and is 
waterproofed with three- 
ply reinforced malthoid 
laid direct on the con- 
crete slab, each layer 
being" placed separately 
and securely embedded 
in hot asphalte. 

For the wearing" sur- 
face of all floors, with 
the exception of those in 
the office rooms, cement 
and sand mixed 2 and 1 
and finished from a steel 
float were used. 

In the office rooms a 
patent flooring- material 

was used, which was laid direct on the concrete in two coats. This material is 
fireproof and very light, thus reducing- the load on the beams. A reinforced 
concrete staircase with a half-landing- leads from the ground outside to the office 
floor level. 

No outside plastering was specified, the whole of the exposed surfaces of 
the concrete being simply finished with two coats of cement wash applied with 
brushes, after carefully stopping all defects showing in the concrete on the 
removal of the boxing. 



Concrete Entrance Steps. 
Reinforced Concrete Power 1 House, Lake Coleridge, New Zealand. 



21 



H. C. GA YFORD. [CONCRETE! 

All window openings were fitted with steel sashes and the internal and 
external reveals plastered up to the frames. The total area of window space 
is 6,ooc sup. ft., constituting- a striking feature of the building. 

The accompanying cross section will serve to show the general arrange- 
ments of which the details are as follows : — 

(a) Main engine-room floor consisting of a 10-in. slab supported on 
machinery foundations and reinforced with f-in. rods at 9-in. centres. 

(b) Basement to accommodate penstock pipes and machinery founda- 
tions built up from basement floor to engine-room floor. 

(c) Draught tube chambers. 

(d) 4-ft. 6-in. culvert connecting draught chamber and weir basin. 

(e) Weir basin for measuring the discharge from each turbine. 
(/) Oil switch and busbar chamber. 

(g) Main switchboard operating gallery. 

(//) Upp-er gallery and battery room. 

(i) Transformer room. 

(/; Three-foot penstock pipes to turbines. 

(ft) Reinforced concrete crane beams. 

(/) 20-ton travelling crane. 
The total amount of concrete in the building is 2,700 cu. yds., and the per- 
centage of steel to reinforced concrete worked out at about 89 per cent. 

At present the only defects .showing in the work are small vertical hair 
cracks in the 9-in. and 4-in. curtain walls caused through expansion and con- 
traction. The cost of the building was ^15,800, and the work was carried out 
by local contractors acting under the supervision of the Assistant Engineer, w T ho 
was in charge of the whole of the construction works. The designing of the 
building and the calculation of the stresses were carried out by members of the 
electrical engineering branch under the supervision of the Chief Electrical 
Engineer to the Government, Mr. Evan Parry. 



2 2 



f J r IDNS I L'liri IUNAI .1 



RECENT lililTlSH PATES 



My. J. 



RECENT BRITISH PATENTS 
RELATING TO CONCRETE. 

We propose to present .it tntervats ps.tHatla.rs of British Patents issued "> connection 
vttth concrete ana reinforced concrete* The last article .ippt'.ircj (n our issue <// 
er, 1*1-1. ED. 

Centering for Concrete Floors, etc. No. 240, 14. J. II. Brocktnan, " Lynton," 
Ashbourne .1 ;'<•>//<<', Blundellsands , Lancashire. Accepted September 24 14. This 
invention comprises an improved form of centering for giving tin- proper contour to 
floors, ceilings, arches, vie, which can he removed when the work has se\ solid and 
then re-used. 

The centering consists of a 
piece of metal (.1, Fig. 1), with 
corrugations (/>) in it, the end por- 
tions (C) having the crests of tin 
corrugations so folded .'it b that they 
become level with the hollows />', 
and so form flat portions which are 
bent downwards so as to taper 
slightly outwards, while the extreme 
ends are bent laterally outwards to 
form flanges (/.)). An inverted 
trough-shaped centering is thus 
formed, the upper or unbent portion 
being corrugated, while the sloping 
portions (C) and the lateral flanges 

(/)) are flattened. The crests of the corrugations can be folded as shown either in 
Fig. 4 or Fig. 5. In either case the metal has three plies or thicknesses at the pleat 
which strengthens the flattened portion and enables it to be bent downwards, and also 
facilitates the centering being removed when the work has set. 

In use a number of these centerings are placed end to end overlapping one 
another and in rows spaced apart. A piece of wood or other suitable material (E), 
Fig. 3, is placed between each row, to which the lateral flanges (D) are nailed or other- 
wise secured. Concrete (F) is then filled into the spaces between the inverted troughs 
and on top, and is reinforced in any suitable way, as by bars (G) having wings ill). 
When the concrete has set, the centering is separated from the pieces of wood (E) 
between each row, which remain in position, while the centering is removed without 
injuring the concrete work. 

If desired, the flattened portion can be flush with the outward crests (B) of the 
corrugations, instead of with the inward crests (b 1 ), and the shape of the centering 
can be varied. 




.Tou/; 3. 





m 



tty.4. 



JlUf.5. 




23 



RECENT BRITISH PATENTS. 



iCONCREXEJ 



Reinforced Concrete Walls. — 

No. 522 14. //. J. Walduck, of Walls, 
Ltd., Crown Galvanising Works, 
Fazeley Street, Birmingham. Accepted 

October 15 14. According to this in- 
vention vertical walls, partitions, and 
floors of concrete or similar material 
are reinforced with corrugated ex- 
panded metal work, the corrugations 
having a depth nearly, but not quite, 
equal to the thickness of the wall or 
part to be reinforced. 

These sheets of expanded metal 
(a, Fig. 1) are, in the case of a wall, 
arranged so that the corrugations are 
in a vertical plane, and uncorrugated 
sheets of expanded metal or wire work 
(b) are placed on one or both sides, the 
outer surfaces of the wall being plaster 
or cement applied to the flat sheets of 
expanded metal work. 

In constructing the wall, the cor- 
rugated sheet (a) is placed in position 
for the full height which the wall is to 
have, and the plain or uncorrugated 
sheets (b) are then placed in position 
and secured on opposite sides of (a) for 
a short height only. Concrete is then 
poured into the spaces between the 
corrugated sheet (a) and the plain 
sheets (b) to practically the full height 
of these sheets. Additional plain 
sheets (b.) are then applied to the cor- 
rugated sheet (a) so as to increase the 
height of ihe plain sheets, and concrete 
is poured down the spaces so as to fill 
up the corrugations in the sheet (a). 
height. 



/r*0. / 




Fig. 2 




In this way the wall is built up to its full 



Boards may be arranged on opposite sides of the metallic reinforcement employed 
so ;i^ to form a temporary mould for the reception of the concrete. When this has 
hardened, the boards are raised to bring them opposite parts of the reinforcement to 
which concrete has still to be applied. 

Manufacture of Cement. — No. 17,^73/13. L. P. Basset, 43 bis rue des Ches- 
neaux, Montmorency, France. Accepted August 7/14. — The present invention has 
for it> object a process for making cement from calcium sulphate, occurring commonly 
in the form of gypsum, enabling the complete decomposition of the sulphate of calcium 

to be obtained, and at the same time 




2, 





parts of cement the following proportions may 
24 



avoiding any trace of sulphide re- 
maining in the cement. The 
characteristic feature of the invention 
is that Ihe complete decomposition 
of the sulphate of calcium is 
obtained by Ihe production of an 
excess of sulphide of calcium, and 
this excess of sulphide is then 
reduced by oxidation, obtained by 
an excess of air in the furnace in 
which the operation is carried on. 
In the manufacture of 1,000 
be taken : 



j r CONMPlHTIONAl. 
«ihN01Nll kMNC. — , 



RECBS / lih'ITISII PATEh 



1,580 pai 
35° 



I )i \ sulphate of calcium 

Drj claj 

( lharcoal ( 1 he like matei ial) 

In order, then, to destroj th< excess "l sulphide b\ means "I oxygon, a abov< 
indicated, the Furnace should, in the roasting 01 second zone, work in an oxidi 
atmosphei e, 

A furnace foi carrying oul the process consists of a rotating cylindei (< 1 ol :■ 
jength, the ends of which enter two fixed chambers (</ and e) 

In the first chambei is arranged a shoot (D conveying the paste formed l»\ the 
mixture oi clay, sulphate <>l calcium, and a little charcoal 01 equivalent substance, 
and a discharging conduit (g) opening into the chimney. 

In the second chamber the discharge for the treated products is shown at (//j. 
Carbon monoxide or other reducing agent is injected by a tuyere (/) and air in ex< 
is introduced by a tuyere (/'). 

In all the zone (a) to the right of the tuyere (t) the atmosphere is reducing; under 
the anion of the carbon monoxide contained in the gases of the furnace, and ol the 
charcoal or the like contained in the paste, a certain quantity of sulphate is transformed 
into sulphide, and this sulphide is found in excess. 

On passing to the left of the tuyere the material encounters an oxidising 
atmosphere, which causes the decomposition of the sulphide. The roasting of the 
cement is effected near to the tuyere (/), where the highest temperature occurs. With 
this new process either sulphurous acid or sulphur can be recovered as by-product. 

Sewers and Conduits.— No. 

17,447 13. F. Thackeray, 3, Cam- 



rt* 




ft- 



uz^u 




-^ 



brian Terrace. Gwaelody garth Road, 
Merthyr Tydfil, Glamorganshire. 

Accepted January 22/14. — This in- 
vention comprises a construction of 
sewers, conduits, and culverts by 
using curved slab linings, which 
form a permanent part of the 
sowers, and are bound with wire 
and cased with concrete, which may, 
if necessary, bo reinforced with iron 
or stool bars. Fig 1 shows a cross 
section of a circular-shaped sewer of 
this kind, and Fig. 2 shows a part 
elevation. 

The curved slabs (A), con- 
veniently, but not necessarily, six in 
number, may be of varied sizes, and 
may be made of concrete, earthen- 
ware, or like materials. Some of 
the slabs may be made of one 
material and some of another, and 
those made of burnt clay may bo 
glazed on the concave surfaces, 
while those of composition may be 
reinforced with wires or wire netting 
imbedded in them during manufac- 
ture. These curved slabs support 
the surrounding concrete during the 

fresh, soft, wot condition of it as laid in situ. The use of special centering tackle is 
obviated, and when fixed in position the slabs are simply jointed with cement and 
bound with wire belts (£), and the ends of each piece of wire forming a belt are 
twisted together. 

If additional strength is required to support the sewers, etc., on account of the 
soft nature of the ground, or from other causes, the concrete (C) may be reinforced by 
iron or steel bars (D) embedded in the lower part of it, and may be further reinforced 
by bars (E) where required. 

The cross-sections, instead of being circular as shown in Fig. 1, may be elliptical, 

25 



<*'* 2- 



RECENT BRITISH PATENTS. 



fCCT^gTE] 



k 


' 


'« 


^~' t-v — -1 




y 




I Fie 


|1 




y 


S 












s 


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1 


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i 








s 
















'M J 








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\ 



oval, or egg-shaped. During and after construction holes may be formed in the slabs 

and concrete for junction pipes, vent pipes, etc., or junction blocks may be built in 

for this purposi ■ 

Reinforced Concrete Warehouses. — No. 28,584/13. P. 7". /. Esther, 15, Dowgate 

Hill, Cannon Street, London. Accepted August i~ 14. — This invention relates to the 

construction of walls of reinforced 
concrete building's designed for 
warehouses, store rooms, libraries, 
etc., and consists in constructing 
them in such a manner that the 
walls themselves form shelves, bins, 
or hoppers for the reception of 
goods. 

Figs. 1 and 2 show sections of 
outer walls of a building, Fig. 3 
shows a section of a partition wall, 
and Fig. 4 a section of part of a 
building. 

Sheets of iron or steel (a) are 
strung together on rods (c). The 
shelves (/) have their backs (b) 
elongated and sloped downwards 
oyer the hooks (c), and the inter- 
spaces are filled with concrete, thus 
making a wall combined with 
shelving. In Figs. 1 and 2, which 
are sections of outer walls, addi- 
tional bolts (c) and bent plates (;') 
are employed. All these bent plates 
can, when required, be perforated 
for the better securing of the con- 
crete. 

The outer walls, and, in some 

cases, the inner, can be built in 

sections or nests, the interspace 

being filled with concrete, as shown 

at (il/), Fig. 4. The flooring between 

_ _ „ room and room can be treated in the 

y J same way, as shown at (A). 

Struts for Excavations and Concrete Shuttering.— No. 449/14. F. W. Wale. 

Tunbridge, Wolseley Road, Wealdstone, Middlesex. Accepted August 7/14. — This 

invention relates to improved struts for supporting the timber that retains the soil in 

place in excavation work, or main- 
tains in position the moulding 

boards used when making concrete 

walls. 

The strut comprises a pair of 

abutmeni members (a and b), one 

of which has a right-hand and the 

other ;i left-hand thread. Each has 

;i bead (< j at its out* r end provided 

with sharp projections (d) to engage 

i he struct lire to whi< h the strut is 

applied. 'I he members <i and b are 

held together bv an elongated nul 

(e), which h.-is internally-screwed 

portions (f and g) to engage the 

right- and left-hand screw members 

a and b, and on the inn* r ends of 
• ~i rew hm mbers pins or pro- 
jections (// and f) are situated to 

prevenl the normal complete separa- 
tion of the pai t -. 
26 






RECENT BRITISH pate: 



,'a constuUCtRKVD 

[k mo pga i n^^ 

Thee.ong W « ave tl tral ^^^'ZX ' ifrSdffcd 

inserted to tarn h and so effecl adjustment ol ""/.;,,",, tt ,„.,, , ,„;„ 

constructions H maj be ol I la, f« having a n aper "' . ,,', "' win-n the stru'i 

be inserted, 01 il maj be ol angulai form to I"- urned by a span 

is req uired to, forms, shuttering or bordermg l'-' - 'I- ^/l". ,„,, , ,„,!„. tie 

condition, additional support is proy.ded b> mean^ o bars £an d | ^ _ 

in anj citable manner, as, ot instance, by s " ' h ,„''„„,„- „ linary 

then passed through the moulding boards and secured in posi 

wing nuts. 

\ ,,si> i' E Coienet, 20, rue de Londres, 
Concrete Subaqueous Structures.- \' "'°' z .' •,',,,.„',„,,) main elements, such as 
;...„-.,. Accepted August , ■+ Aeeording to ^J"™^™™ „,, ,,,,. ,,, and 



1. 



w/s/;ws, '■ '/)»w//, '///< ■'///, ~ ' 





Ai 



gmnM^> 



> ues o r sheet piles (a, Fig. u, and 
supplementary members, such as ties, 
stays, or like members (d), are provided 
each with one part of a dovetail or Uke 
joint, the arrangement being such that 
the stav, tie, or Like member is coupled 
to the "■(•lenient by the interlocking of 
the joint parts. 

The invention is described with 
reference to (a quay wall formed of 
sheet piles (a), an anchor slab (b), and 
two super-posed series of ties. 

Fig. 3 shows an enlarged view of 
one of the ties (J), and Figs. 4 and 5 
are respectively a second elevation 
and an inverted sectional plan (in two 
planes) of that part of a sheet pile to 
which a corresponding tie is to be 

joined. 

The ties (d) to be used are so 
formed that each comprises at the end 
to be assembled under water a head (d 1 ) 
which is of dovetail shape. The re- 
inforcement is suitably designed 'o 
correspond to this shape, but is not 
allowed to project beyond the surface of 

the head. 

The sheet piles (a) adapted to 
engage with the ties (d) are formed 
with projecting members (a 1 ), provided 
with recesses which in plan have the 
same shape as the heads (d 1 ) of the 
corresponding ties. The members (a 1 ) 
may be suitably reinforced, the re- 
inforcements being arranged so that the surface of the point is uninterrupted by 
projections. . . 

The various parts to be used are erected in the usual manner, exception being 
made with "regard to the setting in place of each tie (d) and the positioning of he 
h Jad (di thereof. The tie heads fa) may be formed during ^^^^C^nS 
rings (A so that ropes may be attached for lowering the ties into position; the ring. 
alsS serve to identify the face of the tie which is to be arranged uppermost. 

In assembling the parts, each tie (d) is lowered so that its head (*0™y slide 
vertically along the sheet piles with which it is to be assembled. The head of each 
tie thus' lowered is forced into the recess of the member (a ). 

Shear Reinforcements.- So. 15,309/14. The British Reinforced Concrete 
Engineering. Co., Ltd., 82, Victoria Street, Westminster, London, and A G. BjO^aM. 
AcTe^Zoctoler 22/14. According to this invention the cotters which are driven m 

27 




RECENT BRITISH PATENTS. 



[ CONCRETE 



between the loops of the shear members and the 
longitudinal reinforcing bars of a reinforced concrete 
structure are of improved shape, to prevent the shear 
members altering their positions on the bar during the 
ramming in of the concrete. 

The shear members are usually in the form of 
short steel rods, which are bent round the longitudinal 




&€#. ft. 



reinforcing bars. 

Several alternative forms of cotters are 
described. In one form (Figs. 1-3) the cotter 
consists of a strip (a), preferably tapered in 
plan, of thin sheet metal (usually malleable | 
steel) which is folded back upon itself, so that'' 
the bend forms the thick end of the cotter 
and the two ends of the strip the thin end. j 

After being driven in until the loop (b) of 
the shear member is held firmly to the bar (c), the upper thickness of its narrower end 
is bent upwards and caused to lie immediately in front of and against the loop (&), thus 
preventing slackening of the cotter with subsequent operations. 

Figs. 9 and 10 show different methods of application of similar bent-back cotters. 

The cotter may also be made of a slitted solid wedge-shaped piece of metal instead 
of a thin piece folded hack upon itself, as shown in Fig. 14, the centre or the two 
outer tongues being bent upwards. 

In a further modification the cotter is formed of a piece of bendablc metal tapered 
in plan, but of even thickness from end to end, which at its narrower end fits the bar, 
but ;it its wider end is bent to afford a " three-point " contact with the bar and 
loop (Figs. 16-18). 



2H 



fo\ CONSTBI.'CTIONAI} 
I* V KNQlNKFJ/lNfi — ,1 



THE ACTION OF BOILING WATER. 








THE ACTION OF 
BOILING WATER 
ON CONCRETE. 



By PROFESSOR E. R. MATTHEWS, A.M.Inst.C.E., F.R.S.E. 

(Chadwick Professor of Municipal Engineering in the University of London). 

The action of boiling water on Concrete is a question of considerable importance in 
connection 'with certain works, and the following short article will doubtless be of 
interest to engineers. — ED. 



Tanks constructed of concrete or reinforced concrete are often made for the 
purpose of containing hot water, especially in connection with chemical work's, 
and the effect upon the concrete of immersion or partial immersion in water at a 
temperature of boiling- point is one which should be seriously considered. 
\\ nilc many experiments have been made to ascertain the action of hii^h and 
low temperatures upon concrete — such, for example, as the effect of frost on 
concrete, and the result of subjecting- concrete to excessively high temperatures 
(dry), there appears to have been no thorough investigation with a view of ascer- 
taining whether hot water strengthens or weakens concrete. 

The author's attention was drawn to this in a practical way at Bridlington. 
While serving- as Borough Engineer of that town he constructed (about four 
years ago) at the upper waterworks, and adjoining the boiler house of the new- 
pumping station, a concrete tank for the purpose of receiving the waste hot 
water from the boilers. This was of plain concrete, and the dimensions were 
approximately, depth 6 ft., length 4 ft., width 3 ft. ; thickness of walls about 
9 in. at top and 14 in. at bottom ; thickness of concrete floor 6 in. The tank 
withstood the ill effects (if any) of the boiling water well, but the cement in 
the joints of the sanitary pipe drain which he connected to this tank, and 
through which drain the hot water from the tank discharges, showed, when 
opened out and inspected by him about four months ago, and for some 
unaccountable reason, that the cement had deteriorated, and that several of the 
joints were in consequence leaky. A one-to-one (cement and sand) mixture was 
used for these joints, and the work the author was assured was done well, 
although the pipes were not subjected to the water test. So leaky, however, 
were the joints that the drain had to be taken up and relaid. It was laid 
through chalk. The cement certainly showed that it had deteriorated. 

The author took the matter up with the firm who supplied the cement, and 
was convinced that it was not the cement that was at fault. Thinking that 
probably the action of boiling- water on cement was deleterious, he asked 
Messrs. G. and T. Earle, cement manufacturers of Hull, who had previously on 
several occasions carried out tests for him, if they would undertake to investi- 
gate this matter of the action of hot water on concrete. They kindly agreed 

29 



E. R. MATTHEWS. 



(CONCBKlTiJ 



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[|llraHiI§tj§ THB ACTION OF BOILING WATER 

to do so, and the accompanying tabulated statements sel forth the results ol 
their investigations, and are exlremelj satisfactory and assuring*. The tests 
clearly show thai instead ol weakening concrete, hot water, up to .1 period <>l 
three months .it anj rate (1 cannot saj what takes place beyond thai period, but 
there is even reason to believe that il .1 detrimental effect was likeh to occur, 
it would have shown itsell 1>\ the end ol three months) increases in compressive 
strength Portland cement concrete. 

I he experiments were carried out in three diffcrcnl scries and at different 
time, . 

fable I shows the actual results ol the crushing ol the 6 in. cubes. 

Table 11. gives the average results worked out in tons per square foot. 

Conclusion. — Allowing for slighl irregularities in the results, the tests show 
that, ii concrete is allowed to harden for seven days, and is then boiled for seven 
days (which is certainly a severe test), it shows a compressive strength at the 
end of the fourteen days, which is only attained at three months when the 
concrete i> left in air; when the concrete is immersed in water the equivalent 
strength would appear to be attained sooner, possibly some time between one 
and three months. 

It must not be assumed that these results are final, although they certainly 
would justify us in concluding; that the idea that hot-water weakens concrete is 
an erroneous one. 

Testing Laboratory Notes on the Cement used. 

Citbcs and Briquettes filled August 7th, 1914. 
Tensile Strain. 

Moulds filled with thumb pressure, i day 7 days. 28 days. 

in air, 6 days in water. Xeat cement, 1 in. section . . . . 705 lbs. . . . . 760 lbs. 

Moulds filled by hand with small bi 

rammer, 1 day in air, 6 days in water. Meat cement, 1 in. section .. .. S25 lbs. .. .. 930 lbs. 

Moulds filled using Standard B ehme 

hammer, 1 day in air, 6daysin water. 3 standard sand, 1 cemen.t 1 in. section 410 lbs. . . . . 510 !bs. 

Moulds filled by hand with small trass 

runmer, 1 day in a r, 6 davs in water. 3 standard sand, 1 cement, 1 in. section 500 lbs. . . . . 600 lbs. 

Compression Strain. 

2| in. cube mould filled by hand with 

small brass rammer ; day in air, C 25 8 tons, 170 tons 32-8 tons, 609 tons 

davs in water . . . . . . . . Xeat cement . . . . . . . on sq. ft. on sq. it. 

« in. cube mould filled, using Kleb 10 -8 tons, 200 tons 15-2 tons, 282 tons 

himmer, 1 day in air, 6 days in water. 3 standard sand, 1 cement . . . on sq. ft. on sq. ft. 

The lead-sealed " Pelican " brand of cement used is ground to the following fineness : 2 per cent, residue on 180 sieve— 
i.e., 32,400 holes to the sq. in. 



3' 



CONCRETE FOR ORNAMENTAL GARDEN WORK. [CQNCBETE 






a ? 




Concrete Seat. 



i^^^^^^^^^^SS^^^^SS^^^^^^^^Si^^^^^l^SsgS^t 



CONCRETE FOR ORNA- 
MENTAL GARDEN WORK. 



as 



m 



il an! aaarflpjTj^n an! y$= 



i SaS 



; Lie uc (U£ BE US BE IE IE 

B an] sn an an] an an! anl arfl 



For //ze following illustrations and particulars of concrete 
nvork suitable for garden decoration, nve are indebted to the 
44 Concrete-Cement Age " of Ne<w York. — ED. 



^ 



Concrete is undoubtedly becoming- more and 

more popular for decorative outdoor work, and 

the illustrations we are able to reproduce gave 

an excellent idea of the many uses to which it 

can be put. All the work illustrated in this 

article has been carried out on an estate in 

Philadelphia under the direction of Mr. Adolph 

Schilling - , and we are able to give a short 

account of his methods on a later page. 

The illustration in our heading" is from a photograph of a concrete seat in 

front of the pergola, the griffins at each end being" specially well modelled. The 

various flower urns and flower boxes need no description, but are interesting- as 

showing what can be done in this way. 

The columns in the pergola are of massive cast stone, and a second pergola 
which we illustrate has four cast-stone statues, emblematic of Spring, Summer, 
Autumn, Winter. The outlookers and rafters of this pergola are cedar logs, 
which rest directly on the statues. In another view we show three of these 
stat ucs in better detail. 

The plain work of all these was cast in pla.ster moulds and the ornamental 




' onci eti F lowei Vai i 
i i! fob Ornamental Garden Work. 



32 



P^SSSlNotij CONCRETE FOR ORNAMENTAL GARDEN WORK 



undercut work in gelatine moulds. Aftei casting', ;ii the age ol io days, thi 
pieces were immersed in large tanks holding an acid solution, until the ouler 
cemenl coating was removed. I lii^ treatment left a fine-grain texture similai 
to rubbed stone, and shows the aggregate i<> besl advantage. The general 
colour tone is .1 warm grey and ivory, resembling in ever} respect the marble 
ornaments <>i the old gardens ol Europe. 

The following is an <x j r.ni from Mr. Schilling"^ paper <>n his methods in 
ornamental concrete work : — 

Colour Effects. IO produce colour effects we may us< the grey and 




Concrete Flower Urn. 
Concrete for Ornamental Garden Work. 

white Portland cements, either by themselves or mixed in certain proportion, 
adding- to them suitable pigments. But in many cases the natural-coloured 
aggregates, sand, silica, pebble grits, marble and granite, will give excellent 
and more uniform results. The importance of mixing the pigment thoroughly 
with the cement, before adding - the aggregates, should be appreciated by 
anybody attempting to make concrete in colours, and there should be great 
care to avoid undue weakening of the cement. 

As a very simple method to test the proper amalgamation of the pigment 
with the cement, take a handful of the mixture and press it under a sheet of 
stiff paper. This will produce an even surface of the material, and as long as 

n 33 



CONCRETE FOR ORNAMENTAL GARDEN WORK. [CONCRETE ! 

this surface docs not show absolute uniformity in colour the mixing is 
ire tmplete. 

The absorptive qualities of concrete during its stage of curing and seasoning 
offer opportunities for colouring concrete products by capillary action. By 




Interior of Petgola with Concrete Columns 




( oncrete Pergola View from the Garden. 

1 ' ' ' "i ' »i .'■ mien i \i. Garden Work. 



1,n ; m ; ,llofl Hil colour is deposited in the pores of the surface, amalgamating 
u,il1 ""■ """""' in a pcrmanenl unit. The possibilities of this treatment are 
, '" , " m ""' 1 "" ^dividual knowledge of colouring values, and judgmem so as 
impair the strength requirements of concrete, are essential Uu- success 



34 



[k^fS&SK!"! CONCRETE FOR ORNAMENTAL GARDEN WORK. 



Penetration Method oj Colouring. ( olouring solution can be made to 
penetrate the surface ol concrete six inches or more, if the object is placed in 





^^BJ( 




Concrete Flower Urns. 
Concrete for Ornamental Garden Work. 



the- solution in a very green state. It is rarely necessary to penetrate more 
than ) 32nd in. to £ in. , this thoroughly tills all pores, gives the desired coiour 
effect, and is le.^s expensive. Every atom of colouring- matter absorbed by 

D2 

35 



CONCRETE FOR ORNAMENTAL GARDEN WORK. 



[CONCRETE) 




General View of Pergola and Seat. 
Concrete for Ornamental Garden Work. 

the concrete reduces the strength of the solution ; and as some of the colouring 
matter used is quite expensive, good judgment in allowing only the necessary 
absorption of colouring matter is advisable from an economic standpoint. 

Aniline colours and the sulphates of copper and iron are the most suitable 
to make solutions in which to colour concrete by the capillary method. The 
concrete to be coloured can be treated after it is several days old. Concrete 
products with strength requirement should not be subjected to the colouring 
bath until the concrete has attained its required strength, as the filling of the 
pores in the concrete stops the action of its curing by the usual methods. 

Colouring by absorption is effective on surfaces of concrete after it comes 
cut of the mould, or after being treated with acid or tools. Surfaces that have 
been coloured by absorbing mineral or metallic colours become waterproof, and 
the action of the weather 
on the metallic colours is 
the same ;is on real 
metals, increasing the 
beauty of colouring by 
the usual oxidation 
noticed on bronze or 
copper. Surfaces ol 
con< rete treated by this 
method become so hard 

and dens-- thai they will 
take a uniform dull or 
high gloss polish. I h.i\ e 

treated SUCh SUrfai 

in the same man 
as marble, granite, and 
metal, under polishing or 
buffing mat nines. 

36 




Concrete Figures in Pergola showing details 
1 omcr] ii 1 "i Ornamental Garden Work. 



AtSoKKil'Sffti] CONCRETE FOR ORNAMENTAL GARDEN WORK 



Products made b) these methods, such as ftowei pots, vases, and boxes, 
Ul " hold water after the second da) of casting-, and become so hard thai when 
struck with .1 hammer the) sound like .1 metal bell. I do nol think water- 
ing compounds are essential in obtaining this result, but consider the proper 
amount ol water and thorough grading .is .ill important. I have obtained excel- 
teni lu< » find three colour effects by painting certain parts <<! objects before 
subjecting them to the colouring bath. The parts so coloured would nol be 
affected by the 1 olour in the bath. 

The artistic possibilities of such treatment are limited only by the colour 
sense and taste employed by the craftsman. By using certain non-absorptive 




Pair of Concrete Flower Boxes. 
Concrete for Ornamental Garden Work. 



aggregates, their natural colour can be retained, while the absorptive parts will 
assume the desired colour. In this treatment certain precautions must be taken 
not to use certain acids in washing- before immersion in the colour bath, as trie 
chemical action of the acids is likely to counteract the colour value of the bath. 

I find that concrete of proper age can be treated just like any natural 
stone, using - the same tools and machinery to dress its surfaces, and it is my 
strong- conviction that the success of concrete stone for building" purposes rests 
with a close affiliation of the stone-caster and the stone-cutter. In this way 
alone shall we be able to give concrete proper texture and the necessary qualities 
of dimension stone, so essential with the architect and builder. 

Acid Baths. — For acid baths, tanks of sufficient size should be constructed 
in a concrete shop, and the soaking of concrete surfaces in acid will not only 
result in a great saving of acid, but produce a class of work that cannot be 
obtained with the scrubbing- brush. This treatment preserves the edges and 
details of designi, and makes the surface uniform. Any of the hard spots not 

37 



CONCRETE FOR ORXAMEXTAL GARDEN WORK. 



[CONCRETE] 



sufficiently affected by the arid bath ran be treated separately after the article 
has been Hushed with clear water. Care must be taken that aggregates <>f the 
surfaces are of nearly uniform hardness, or the acid will eat the soft portions 
out before the harder particles have been cleansed of the cement coating. I 
have had some very fine work spoiled when, to obtain a certain fine effect, I 
mixed black marble (a limestone) with crushed granite. The acid bath left only 
the spaces where the black marble had been, while the granite showed a very 
fine texture and natural colour. 




Concrete Garden Seat. 
Concrete for Ornamental Garden Work. 



3* 



i 



, CTON.vrkMKTIONAL 
KNdlNl.l NlN(i — , 



DEEP WATER CONCRETING. 




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£• -'i 



- 0g$? 



DEEP WATER CONCRETING 
THROUGH A TUBE, 




Notes on the Tremie Method and Suggestions of Various 
Expedients to Avoid the Difficulties Likely to be Encountered. 

By E. B. Van De GREYN. 

We publish beloiv < slightly abbreviated) an article ivhich has appeared in the 
44 Engineering Record " on Deep Water Concreting, thinking the matter may be of interest 
to some of our readers.— ED. 



Some time ago in a short article on the method of starting deep-water concreting 
through a tube it was stated that " as is well known, unless the tube is sealed 
in some way the cemenl will wash out during the downward passage and leave 

only a pile ol stone and sand. This waste of concrete may in the case of a 
12-in. tube 30 it. long amount to more than 1 cu. yd." 

It is plain that if the tube is filled by dumping little batches (such as wheel- 
barrow loadsj the concrete in each small batch will be washed until the water 
in the tubs is absorbed or forced out at the top. If, however, a large batch 

of concrete, sufficient to fill a con- 
siderable length of the pipe, say 
30 ft. or 40 ft., is dumped at one 
time into the hopper of the tremie 
1 would not expect the concrete to 
be washed as stated above-— that is, 
il the procedure of charging- out- 
lined hereafter is followed. 

Experimental Tremie. — A 

lab iratory experiment with a minia- 
ture tremie was tried by the writer. 
The tremie consisted of a glass tube 
1 in. in inside diameter and 12 in. 
long and a tin funnel cut to fit the 
top. A china plate was placed in 
the bottom of a water bucket partly 
filled with water. The glass tube 
was clamped to a standard with its 
lower and 5 in. below the water sur- 
face and § in. above the china plate. 
A batch of mortar was made up 
of 1 part of cement and 2 parts of 
standard Ottawa sand, the mortar 




VW777Z77Z7777?. > / /}77>y}'///, OM /////'//; 

F '9-' Fig. 2. Fig. 3 

Tremie Empty, Sealed and Ready to be Shipped, 



39 



E. B. VAN DE GR1-YX. [CONCRETE ] 

being made quite wet so as to flow freely through the tube. The batch of 
mortar was dropped into the hopper several times with the same results. In 
each case the water was driven out of the tube ahead of the mortar and the 
mortar spread out over the plate and tilled the lower part of the tube. In each 
case there was no washing out of cement. The mortar extended about 5 in. 
up in the tube. A depth of water of 5 in. is small compared with 40 It. or 
50 ft., but the experiment shows what might be expected. 

Sealing the Pipe. There is no doubt that preliminary sealing of the pipe 

in some way is the safe way to proceed to charge the pipe for the first time. 
Under certain conditions of concreting under water I would consider that a layer 
of shavings and sawdust with a layer of cement on top should be placed in the 
pipe before starting the concrete, but in some instances the plug might be 
dispensed with. For example, consider the conditions on one job under the 
writer's charge. A large open caisson had been sunk to a depth of about 50 ft. 
below water level in alluvial soil, the caisson had been dredged out and piles 
driven within, and finally the soil that was forced up during driving had been 
removed. The excavation was carried a little lower than depth required on the 
plans. The concrete placed immediately on the bottom would mix with the 
mud and form a base for the remaining concrete required on the plans, and 
due to the large mass of concrete to be placed in the caisson it was not necessary 
often to change the position of the tremie in a horizontal direction. Under 
such conditions I believe charging the tremie according to the method outlined 
below was ample protection against washing out of the cement. 

The following method of deep-water concreting has been used under the 
charge ol the writer : Inspection after pumping out the water has always 
revealed the top concrete Lo be first class. The method and equipment, together 
with precautions to be observed, are submitted with the hope th.it some of the 
ideas may be of benefit to those who may find themselves for the first time in 
charge of such work. 

A tremie is shown in Figs. 1, 2 and 3 made up of sections of water pipe 
with bolted flange connections and a metal hopper large enough to hold one 
batch 0! concrete. The hopper is bolted to the top section of the pipe. All 
< onnections are made watertight by means of gaskets. An 8-in. pipe has proved 
practicable and has the advantage over larger pipe in being' lighter. 

On one job the tremie was raised and lowered with the hammer line of 
the pile driver stationed on falsework over the caisson. This proved very satis- 
factory, as the up-and-down movement ol the tremie was under perfect control, 
and such Control is important in tremie work'. On another job the tremie was 
suspended from the load line of a barge derrick. This proved serviceable, but 
not so satisfactory as the pile Iriver because ol swaying ol the tremie due to 

Wave a* lion on tin barge and due to tipping ol the barge at the time of raising 

the tremie. 

In < harging the licinie a large batch capable of filling a considerable length 
of the pipe should be discharged into the hopper at one time. Where the 
contractor is not equipped with a derrick a contractor's cart holding a large 

enough batch could be used, or ii wheelbarrows are used a hopper with a trap 
40 



(JhSBBSmBB I DEEP WATER CONCRBTINi 

door would serve the purpos< oi discharging .1 large batch suddenl) into the 
tremie hopper, Vfter the pipe is once sealed the concrete from then on can ix- 
dumped into trcmies in largt or small batches. 

Concrete should he Mushy* Concrete deposited in deep water through ;i 

pipe should be oi .1 mushy consistencj in order that it may How easily after 
Leaving the cud ol die pipe under tin- surface ol concrete just previousl) 
deposited; 11 will then spread more evenl) after leaving the pipe, 1 hits avoiding 
the foi mation 0! hillocks and making it unnecessai \ to change the position ol the 
tremie in ;i horizontal direction as frequently as would be tin- case il drier concrete 

weir us: (1. Also, it will not choke the pipe. A little experimenting .it the outset 

will soon indicate how much water should he used in each batch. Alter the 
proper amount is determined it should be regulated by ;i gauge so ;is not to 
vary, consideration being given, of course, to appreciable changes in the amount 
of moisture in the aggregate. 

Mushy concrete deposited in water should have an excess of cement. There 
is ;i loss ol cement due to the excess water in the concrete finding its way out, 
carrying a portion of the cement, which is found in the laitance on top. A 
1:2:3 mix is recommended. 

Operation. — In the illustration Fig. 1 shows the tremie ready to receive 
the first batch, the bottom of the pipe 4 being raised from 6 in. to 12 in. above 
the bottom ol the excavation, so that the water may escape as the concrete 
comes down the pipe. It is well to land the pipe on the bottom and then raise 
it, so that one is assured that it is above the bottom. Assume that one batch 
would fill the pipe for a length I — that is, when the concrete begins to emerge 
from the end of the pipe the top surface is at level .1. If the pipe is to have a 
plug of planer shavings and cement they should be in place before dumping- 
concrete into the pipe. Charging- the pipe is the most difficult part of deep- 
water concreting through a tube, hence it should be supervised by some com- 
petent person. If the pipe is dropped before concrete emerg-es from the lower 
end the water in the lower part of the pipe cannot escape and it boils up through 
the concrete, washing- out the cement. Whether a new charge or the absorption 
of this water by additional drier concrete is better must be determined by judg- 
ment, and the amount of such water should decide which will result in the lesser 
waste. If the dropping of the pipe in making the first charge is delayed too 
long- all the concrete escapes, which means that one batch is partly lost and the 
operation must be repeated. After the batch is dumped into the hopper, when 
the surface of the concrete drops to level A, the tremie should be dropped. By 
the time the pipe is dropped to the bottom the surface of the concrete will be 
below level A, as indicated in Fig. 2, and the tremie will be sealed. 

After the pipe is sealed with concrete as shown in Fig. 2 the remainder 
of the pipe and hopper can be filled as shown in Fig. 3. Next the tremie 
should be raised slowly until the concrete flows downward. It is not safe to 
raise the pipe continuously until the concrete begins to flow, because by the time 
the " stop " signal is obeyed the pipe will have been raised too far and there 
will be a sudden rush of concrete through the pipe, with accompanying danger 
that the pipe will not be lowered quickly enough to prevent all concrete from 

+ 1 



E. B. VAN DE GREYS. [CONCRETE 

leaving the pipe and leaving it unsealed. Therefore the tremie should be raised 

a few inches and held, and then raised again a few inches and held, repeating 

until the correct vertical position is found where downward movement will 

gin; the concrete will then slowly lower in the pipe and will emerge tram the 

bottom under right conditions. All this can generally be dune in short time 
and will cause no delay at the mixer, especially after the men become familiar 
with the work. When the surface of the concrete lowers to some level, say c , 
at which it is desired to stop the hVnv, the tremie is lowered and the flow ceas s. 
There is some definite point at which the pressure on the end of the pipe due 
to head of water and concrete outside of the pipe plus the resistance of the con- 
crete to move through the pipe is equal to the weight of the concrete. 
It is to locate this point that the tremie should be raised a little at a time as 
described in the foregoing. Concrete can thus continue to be placed under water 
without passing" through water, avoiding' all wash, emerging" as it does from 
the pipe under the surface of the concrete just previously placed. It is well 
never to I< t the surface of the concrete g"o below the bottom of the hopper, since 
it is then always in sight ; if it is allowed to go below this the next batch confines 
the air in the tube, most of the air bubbling" up through the concrete. 

Precautions. — Se e that all connections are watertight. Lash the several 
sections of the pipe together with cable so as to be able to save them if they 
break loose. Examine the connections whenever possible to see that they are 
not broken. If a connection were broken and the break large enoug r h to let 
concrete through great damage would result by concrete flowing- through the 
break and dropping" through the water, causing" segregation of the constituent 
materials. After starting" concreting- keep it up continuously until completion 
and regulate the moving of the tremie horizontally so as to keep the laitance on 
toj) where it tan be removed later. After the water is pumped out, clean the 
surface of the concrete thoroughly, so as to remove all laitance and furnish 
a good surface on which to start other concrete work. 



V2 



j IWMl'lll MON.U. 



SHEAR AND PROBLEMS ARISING THEREFROM. 




RECENT VIEWS ON 
CONCRETE & REIN- 
FORCED CONCRETE. 



Recent Papers & Discussions. 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method ive are adopting, of dividing the subjects into sections, is, ive believe, a 
neiv departure. — ED. 

THE CONCRETE INSTITUTE. 

SHEAR AND PROBLEMS ARISING THEREFROM. 

By H. KEMPTON DYSON. 

.1 most interesting Paper was presented at the Fitly-second Ordinary General Meeting 
of the Concrete Institute on Thursday, December 3rd. Of this Paper we are <>)ily 
able to reproduce some sliort abstracts. It was very fully illustrated , and there were 
a number of important appendices. 

Modes of Failure of Materials. — That failure of materials cannot occur by 
real compression is fairly evident when we consider the fact that even a liquid 
such as water is practically incompressible. If we apply force from ever) 
direction, we do not cause rupture, as the material is not able to escape 
laterally. A number of experiments were made some years ago at McGill 
University by Prof. Frank I). Adams, and described in the Proceedings of the Royal 
Society, in which marble was placed in steel cylinders and compressed. It was found 
that this brittle material could be subjected to very great deformations without much 
reduction of its strength against thrusting stress, the material, indeed, showing a 
ductile character and ability to undergo plastic deformation when adequately supported 
in a lateral direction. The same thing has been found by experiments on concrete, as, 
for instance, some classic experiments by Prof. Ira H. Woolson. In one, concrete in a 
steel cylinder was bulged out under compression, yet when the encasing cylinder of 
s-teel was removed, the strength was found not to be appreciably different to that of 
concrete which had not been subjected to such deformation. It would seem that when 
complete lateral restraint is imposed, such as by enclosure in a cylinder, the cohesion 
is not developed, but, instead, the crystalline or directional materials undergo distortion 
by slipping on cleavage planes as a strictly ductile material would ordinarily. 

The late Monsieur Armand Considere, in one of his papers on the resistance of 
hooped concrete, referred to experiments in which concrete had been placed to pass 
through the box of a hydraulic ram so as to be subjected to lateral pressure, and at the 
same time was subjected to vertical pressure. It was found that great crushing loads 
were thus enabled to be sustained without rupture. He also refern d to an experiment 
in which that brittle material — glass — could be bent permanently without fracture when 
placed in a liquid under great hydraulic pressure. From this he drew the conclusion 
that the efficiency of hooping in increasing the crushing resistance to concrete was in 
the nature of a lateral support such as might be given by uniform lateral hydraulic 
pressure. The writer, however, thinks it would be more legitimate to regard the action 
of hooping in a different way. 

He would prefer to consider the action to be as follows: The hooping either (1) 
applies a lateral compression equivalent to hydraulic pressure proportional to its 
extension under the lateral swelling defined by Poisson's ratio; (2) after initial cracking 
on the plane of rupture resists lateral motion of the parts by sliding on the plane of 

4> 



THE CONCRETE INSTITUTE. CQNCEETE1 

rupture until failure occurs by the hooping breaking; or else (3) is ol sufficient strength 
not to be able to be broken in this way, in which case the rupture of the concrete is 
confined to that extending between two adjoining hoops, that is to say, the concrete 
fails between the hoops like an extremely dumpy test specimen bedded on concrete. It 
is possible to calculate the effectiveness of hooping in these three respects. 

It is desired to point out that the author has had insufficient opportunity to carry 
this mode of analysis of cohesive granular substance very far. As to how it would apply 
to ductile materials, and as to whether it woidd work out to give much the same result 
as Prof. Rejto's theory has not yet been investigated, nor its relation to the resistance 
of pieces subjected to bending. It is hoped to present further contributions to the subject 
at a subsequent date. 

Reinforced Concrete Beams. — Reinforced concrete beams are quite a distinct 
in themselves, because they pass through two stages in their resistance 
to cross - breaking. In the first stage the steel remains uniformly connected 
to the concrete in which it is cmbeddi d. In the second stage the .steel slips 
throughout the concrete for part of its length and the concrete cracks in 
the ten-ion portion, so that the beam becomes converted into a form of 
nstruction which, in different modes of reinforcing, would appear to consist of 
either a concealed arch with a steel tie, a trussed beam analogous to the trussed timber 
beam, or a frame. Frames subjected to transverse loading are, of course, subjected to 
shearing forces, but the effect of the shearing forces is naturally very different on frames 
from that on a girder with a solid web or upon arches. A shearing force diagram only 
consists of the plotted values of the tendency to shear it asunder which the load exerts 
upon the structural member. We can, therefore, have a shearing diagram equally 
applicable to a beam, an arch, or a frame, But the manner of using the diagram for 
determining the internal stresses which result from the shear forces must be different 
in each case. 

Reinforced concrete beams are quite a special form of construction, because the 
stresses are induced in them in various ways according to different modes of arranging 
the reinforcement, and according to the amount of reinforcement; that is to say, a 
reinforced concrete beam may prefer to act as a flat arch with a tie rod if it is able 
to hold up in such form with less stress than it would in some other fashion. On the 
other hand, if it acts as a beam, the conditions are different in the case where the stress 
is such as not to have ruptured the concrete by tension therein from the case where the 
concrete is cracked. Generally, some parts of all reinforced concrete beams are in the un- 
cracked condition, and really require analysis on the lines of a homogeneous section, the 
materials, however, having different moduli of -elasticity both for the concrete in tension 
and compression and the steel. In the majority of cases the reinforcement is insufficient 
in amount to prevent cracks occurring at some point or points in beams, and then 
wh<n crack- appear it means that the steel has moved in the concrete, and that the 
construction either consist- of a trussed beam or a framed beam in part or in whole. 
Where the reinforcement is inclined at the ends, there is an obvious analogy to a 
trussed timber beam. Such a type of reinforcement is quite appropriate for point loads. 
When the cranked bars are in combination with straight, horizontal bars, a practical 
type of reinforcement is provided which forms a sort of halfway-house, and can equally 
well resist point lo.-ids or distributed loads. In the latter case not only do the straight 
bars produce one sort of beam action, but the cranked rods resist the shear in that the 
inclined pull in tin- bars affords a vertical component at every part of the length to 
resist the shear. 

Cracks thai develop in reinforced concrete beams owing to the excessive stretching 
of the concrete generally follow the lines of the principal stresses, and point to the 
conclusion thai they are the outcome of the diagonal tensile stresses thai become 
developed in ;i homogeneous structure. The very presence of such cracks renders 
illogical the analysis of the distribution of the shear stress in reinforced concrete beams, 
which, I believe, \\;is originally put forward in Germany, and appears in VmL Emil 
Morsch's book on " Der Eisenbetonbau," and also summarised in an appendix con- 
tributed by Mr. William Dunn to the British Joint Committee's Second Reporl on 
Reinforced Concrete; this analysis depends upon the section being homogeneous, and is 
based on the principle thai the shear on vertical planes is accompanied by an equivalent 

•44 



/v^fitVViN?^] SHEAR AND PROBLEMS ARISING THEREFROM. 



shear on horizontal planes. I In sheai is found bj thai analysis to be of uniform 
intensity below the neutral axis ol th< beam, because no normal stress is assumed to 
acl upon the concrete below the neutral axis, and omitting this factoi in th< equations 
I "i shear in homogeneous beams gives th< resull stated, Seeing, however, thai if thcr< 
should be cracks in the beam extending practicall) to the neutral axis, obviouslj there 
can be no Mich horizontal shear stress across iln cracks, and il there is no horizontal 
shear stress therefore vertical sheai stress cannol exisl there either. Indeed, the 
resistance to the shearing force ol a beam must, in the presence nl crai ks, be alt< red to 
the manner in which an arch, a truss, oi a frame resists shearing force. Diagonal 
cracks in nowise preclude the concrete from taking diagonal compression parallel t< 
such cracks. 

Ii was early found in practical work thai il was advantageous to reinforce beams 
against shearing force in other manners than b) trussing members. Rithei ..lone or in 
combination with such inclined reinforcements, web members (edthei vertical or 
diagonal ) were pro\ ided. 

Diagonal Tension and Compression in Beams. The frame action of vertical 
and inclined web members generally belongs to two types. In the firsl case 
where verticil web members are employed the construction becomes a kind 
of N-truss, in which the concrete forms compression members and the steel 
the tension members. In the diagonal form ihe construction becomes practically 
a lattice girder. In both types of construction the frames may be, and often are, 
superimposed; thai is to say, the spacing of the vertical members or of the diagonal 
web members is frequently fairly close. It is possible 1>\ attention to the design to put 
the web members very far apart and yet at the same time ensure frame action.. In that 
ease the concrete diagonals of the frame would become inclined .-it such a flat angle 
that the connection of the concrete to the tension member would not be very efficienl 
unless special means were taken, while the steel would not be so economically arranged. 
If the diagonal compression in the concrete is at a sharp inclination exceeding the angle 
of friction, there is a tendency for the concrete to slide along the bar. This may be 
wholly or partly resisted by grip or adhesion of the concrete to the horizontal members. 
If, however, the inclination is very flat, this sliding tendency becomes great. In order 
to provide resistance to slipping, and for economy, the inclination and the stress of 
diagonals should be kept up, and, furthermore, precautions should be taken to prevent 
the web members sliding along the main tension member. 

If, as has been said, the concrete diagonals are at a flat inclination, the friction 
induced by the inclined compression will be small, and the compression in the web 
concrete will come upon a small bearing area. For these reasons the author does not 
favour, in practice, the use of such very flat trussing, and advocates that web member- 
be not spaced farther apart than the arm of the beam, so as to keep the diagonal 
compression inclined at 45 degrees, which is the most efficient angle for economising 
steel. The whole of the web concrete then becomes effective to take compression, and 
there is little or no tendency of slipping along the bars. Turned-up bars should have 
only slow bends, however, in order to give as much bearing as possible. 

Tin- author suggests that it is better not to adopt variable spacing of the web 
members, but to keep the same spacing throughout, for if we have variable spacing 
the system of superimposed frames, each equally sharing in carrying the load, will 
break down owing to the diagonal web members thereof not being all at equal angles, 
so that we should not be able to say how much was taken by each. 

Another disadvantage in spacing web members far apart is that any point load 
applied between the panel points might cause crippling of the compression boom. 
The web members induce compression in the boom by means of their resolved horizontal 
components, which means that there is a shearing force at every horizontal section of 
the compression boom, but the presence of the compression component means that the 
condition is better than simple, pure punching shear. 

Sometimes there is considerable torsion to be resisted by reinforced concrete. This 
torsion affords pure shear if there are no bending stresses induced at the same time. 

It has been found from tests by Professor Morsch, which have been confirmed by 
the author, that the punching shearing stress in reinforced concrete cannot be con- 
sidered to be resisted to any appreciable extent by members crossing the plane. 

45 



THE INSTITUTION OF CIVIL ENGINEERS. [CONCRETE 



Conclusion. — There are many other aspects in connection with the subject 
of shear. Though a good deal of ground has already been covered, there 
is any amount of room for continued investigation. It should be borne in 
mind that the theoretical analysis of the stresses in materials is in the 
nature of a speculation; it is an attempt, like all scientific theory, to explain 
the facts, but with the progress of investigation further facts come to light 
which cause us to modify the former theory. In that way there is a gradual 
improvement and greater exactitude about theories. Rut their chief purpose must 
always remain to draw the attention o\ the practical engineer to what is happening, 
likely to happen, or what may possibly happen, and in practical design the complica- 
tion of refin -meats in theory are too great to permit of adoption. The practical 
engineer by study of the theory will, however, be able to make his own simplifying 
assumptions for approximate calculations, which will enable an economical and. safe 
structure ;>> be erected satisfactory in all the directions indicated by elaborate analysis. 



THE INSTITUTION OF CIVIL ENGINEERS. 

'The following arc Abstracts of Papers read at the ordinary meeting of the Institution 

on Tuesday, December ist, i<)i-f. 

(i) TESTS OF REINFORCED CONCRETE STRUCTURES 
ON THE GREAT CENTRAL RAILWAY. 

By JAMES BENJAMIN BALL, M.Inst.C.E. 

The Great Central Railway Company have completed within the last six years several 
considerable works in reinforced concrete, the more important of which include a 
bridge carrying a public road oyer their main lines at Ashton-under-Lyne — believed to 
be one of the heaviest reinforced-concrete bridges of its type yet constructed in England 
a bridge carrying a new read and tramway over the Grimsby District Light Railway 
at Immingham dock, and several reinforced-concrete bridges in the dock-area at 
Immingham, as well as a large engine-shed at Immingham dock, the foundations and 
- of which are constructed in reinforced concrete throughout. 

REINFORCED CONCRETE OVERBRIDGE, ASHTON-UNDER-LYNE. 

This bridge consists of parallel girders of three spans. The main girders also 
form the parapets of the bridge. On a level with the bottom booms are formed the 
main deck-beams or cross girders, and between these again are the smaller deck-beams 
parallel to the main girders, supporting the reinforced-concrete decking. The entire 
superstructure is reinforced with round bars on the Hennebique system. 

'I he abutments at each end are of mass concrete, but the piers are braced and 
reinforced. The main girders only rest on the abutments and are not anchored down 
in any way; moreover, they are not continuous, there being a space of 1 1 in. between 
the girders over each of the intermediate supports for expansion: thus each span is 
independent, and consequently any slight settlement which max- take place in the 
abutments or piers will not affeel the stresses on the reinforcement, and in each case 
ih<- full bending-momenl effects due to both dead and live loads were taken into 
aC( ouni. 

B th tensile and compressive reinforcernenl was u-n\ in all the beams, the 
percentage ol reinforcernenl in the main girders being exceptionally high, on account 
of the small area available in the compression flange. 

'lie- bridge was tested with a dead load of i cwt. per sq. ft. and a rolling load 
of two [6-ton traction engines, each drawing a lorn loaded with pig-iron to a weight 
of 32 tons, or a total moving load of 96 tons. In all cases the recover) was complete 
after the load was remove d. 

'I he workingrStresses were limited to 700 lb. per sq. in. maximum compressive 
•''a-- on tie- concrete, and i6,ooq lb. per sq. in. tensile stress on tin- reinforcement. 

rhe actual cost of the work as carried out in reinforced concrete amounted to 
£s^9 1 7- rhe estimated cosl ol a similar structure in steel and masonry was ^8,390. 



^^N-^uriioNAij TESTS OF REINFORCED CONCRETE STRUC7 I RES. 



REINFORCED CONCRETE BRIDGE CARRYING NEW ROAD AND TRAMWAY 
OVER THE GRIMSBY DISTRICT LIGHT RAILWAY. 

This bridge, also designed on the Hennebique system, consists oi a roadwaj 
40 ft. wide, extending ovei two spans ol >j Ft, 2 in. and 31 ft. 2 in. respectively. 
There are five main longitudinal beams 4 , the two outer ol \\ hich also can*) a reinforced 
parapet. The parapets, however, are nol designed to bake am portion <>l the load- 
str< ssi s. 

Between these main beams cross-beams are arranged, which support reinforced 
decking. 

The percentage of reinforcement ranges from o"6o per cent, in the cross beams 
to -|"<>7 per cent, in the outer main beams of the longer span. 

The bridge was tested with two moving tramcars, and no appreciable deflection 
was recorded on any of the beams. 

h was designed to allow for the passage of two 40-ton boiler-trollies drawn by a 
15-ton traction-engine, that portion of the bridge not covered by the moving loads being 
loaded with 1 cwt. per .sq. ft. 

In computing the stresses, the various members were taken as being freely 
supported, and no allowance was made for the continuity of the beams or for the 
fixity of the ends, the allowable working-stresses being the same as in the case of 
the previous bridge. 

The actual cost of this bridge carried out in reinforced concrete was ^2,939. The 
estimated cost of a similar structure in steelwork and masonry was ^3,500. 

FOUR HIGH-LEVEL RAILWAY BRIDGES, IMMINGHAM DOCK. 

These are all skew spans of th<- same construction, each bridge carrying four 
trades over a siding for empty wagons, and forming practically a tunnel 86 ft. long. 

'J "he square span between the abutments is 15 ft. Both the wing-walls and 
abutments are reinforced, and there are in addition reinforced tie-beams at the bottom 
of the abutments, at the same spacing as the cross girders, embedded in a concrete raft. 

The; bridges were designed to carry axle-loads of 18 tons, spaced 6 ft. 6 in. apart, 
or 72 tons on the single-line span. 

The average cost of these bridges in reinforced concrete was ^3,024 each. The 
estimated cost of a similar structure in steelwork and masonry was ^3,800 each. 

REINFORCED CONCRETE FOUNDATIONS AND PITS FOR ENGINE SHED 

AT IMMINGHAM DOCK. 

This work consists of a reinforced-concrete raft, so spread that the load on the 
ground nowhere exceeds 10 cwt. per sq. ft., and the engine-pits form part of the raft. 

The floor of the shed is carried on the pit walls; it consists of a reinforced-concrete 
deck between each of the pits, and is not in any way dependent on the earth filling 
underneath. 

There are in addition fourteen independent reinforced-concrete engine-pits outside 
the shed, of a similar design to those in the shed, but without any flooring between. 

Reinforced tie-beams are provided every bo ft. apart between the pits. 

Kahn bars were used throughout in the reinforcement of this work. 

The actual cost of the work as carried out in reinforced concrete (engine-pits and 
foundations only) was ^8,850. The amount of an actual tender received for brick 
pits on a reinforced-concrete slab was ^.'12,920. An estimate for brick pits on concrete 
carried on timber piling was ,6*15,150. 



(2) CONCRETING IN FREEZING WEATHER, AND 
THE EFFECT OF FROST UPON CONCRETE. 

By JOHN HAMMERSLEY-HEENAN, Assoc.M.Inst.C.E. 

The engineer who is called upon to carry out work in Canada during the winter 
finds that the methods of construction which were satisfactory in the summer will 
need considerable modification to suit winter conditions. 



THE INSTITUTIOX OF CIVIL ENGINEERS. KQsQjETEi 

Concrete work, especially the lighter forms of reinforced concrete used in building 
construction, needs greater can- and supervision. As a result of considerable experience 

gained during the last few years, it can be said that the freezing of concrete will not 
damage it if it has first had a chance to set under favourable conditions for about 
two davs. The effect of the freezing is simply to -delay the process of hardening, 
which will again proceed under suitable conditions, and will eventually attain its full 
strength. If concrete is frozen before it has commenced to set, it will not be injured 
if precautions art- taken to prevent it from freezing again after it thaws until it is 
sufficiently hardened to withstand the effects of subsequent freezings. It is alternate 
freezing and thawing during the process of setting that causes the damage. 

To meet the foregoing conditions when carrying out concrete work in winter it is 

ssary to d< wise means of mixing the concrete with materials freed of frost, placing 
it in the forms before it has commenced to freeze, and then protecting it and keeping 
it warm for about two days. After that it may be allowed to freeze without fear of 
its being damaged. 

In the case of concrete-in-mass, of large bulk, it is unnecessary to apply external 
hear, as the large body of concrete will generate sufficient heat during the process of 
hardening to enable the mass to set ; all that will be necessary is to protect the outside 
of the concrete so as to keep the heat in. This can best' be done by covering the 
concrete with clean straw. 

For light sections of concrete, such as in reinforced concrete, poured at a tem- 
perature not below 22 F., some engineers allow salt to be used in a proportion not 
exceeding 10 per cent. There are many argument:? for and against its use. The 
author prefers not to use it, except in marine works when the concrete is mixed with 
sea-water, and the salt is admitted in that form. He has found that, instead of using 
salt, good results will be obtained for temperatures that do not fall below 22 F. by 
heating the water with a steam-hose taken from the mixer boiler, and when necessary 
placing a few coke or wood fires on the heaps of sand and crushed-stone, the usual 
precautions being taken to protect the concrete when in the forms, as described later. 

For lower temperatures than those referred to above, greater precautions must be 
taken to heat the ingredients by means of steam coils or radiators. 

The concrete having been mixed, and the portion of the work to be carried out 
d< -e:d»-d noon, the floor immediately below it should be partitioned off with tarpaulins, 
and coke stoves arranged under the floor-slab, allowing about one stove to every 800 
sq. ft. of floor-space. All loose dirt and snow must be removed from the forms with 
brooms, and a -.team hose should be applied to remove all ice and frost, the steam 
playing continuously over the forms in advance of the concrete, thus warming them 
in readiness for the concrete. The concrete should be poured quickly and continuously, 
and a^ each section is completed a tarpaulin may be drawn over it, supported on wooden 
strips about 6 in. above the surface of the concrete. In most cases this protection 
will be sufficient, but during very cold weather it will sometimes be found necessary 
to form a sorl of tent over the floor, in which extra stoves are placed to protect the 
workmen and the upper surfaces of the concrete. 

Greal (are must be taken to have the fires kept burning continuously for two 

-, after which the concrete may be allowed to freeze without fear. 

The work must be examined from time to time until it is found to be hardened 
sufficiently. During summer working, the author has allowed the supports from 
the underside of slab> to be removed in four days, but on other occasions four weeks 
have nol been found to be too long. 

'I her*- are many examples of concrete works which have stood the test of time 
without showing any ^ign-> of being affected by frost; but, on the other hand, a l'i w 

- have been reported of very serious corrosion due to the action of frost, such as 
bridge-piers and rein forced-concrete piles. 

Judging from the information available at present, concrete exposed in air in a 
dry locality need not be affected by frost any more than good building stone, and pro- 
bably it will stand much better. Concrete always submerged under water is protected 
and need cause no anxiety. Rut concrete alternately wetted and frozen musi be pro- 
tected from frost. On work which is being carried 011: ;.t Halifax Mr. John Kennedy, 
M.Inst.C.E., is protei ting the concrete pile-, between high and low water with a covering 
of wood about 2 in. in thick nesSj which it is hoped will prevent the action of frost. 

4 x 



r^^NMgiNgtiJ REINFORCED CONCRETE construction. 

THE INSURANCE INSTITUTE OF MANCHESTER. 
REINFORCED CONCRETE CONSTRUCTION. 

By s BROADBENT 

.1 Prise for the best Essay on Reinforced ( 'oncrett Const ruction was ret ently an ardt d 
by the Manchester Insurance Institute to Mr. S. Broadbent. The Essay was read 
at a meeting of the Institute, and wt are indebted to the Insurance Institute 
Manchester for permission to reprint the following Abstract from the Paper. 
In the earlier pari of his essa} the author deals briefly with the earl) histon oi 
reinforced concrete in England. Some remarks arc made regarding compressive and 
shear stresses, the qualit) oi the concrete, and the nature of the aggregate. He then 
goes on to deal with the question of steel, centering, reinforcement for beams and 
columns. 

In the latter portion of his paper he deals with the fire protection of structural 
members. This portion of the paper we give as follows ; — 

THE FIRE PROTECTION OF STRUCTURAL MEMBERS. 

Alter this biief description of the principles and practice of reinforced concrete 
construction, which in view of the space at my disposal must of necessity be a 
somewhat feeble and disjointed effort, a few remarks on the protection against fire 

of the main structural members will not be out of place. 

It is a well-known fact that concrete, when subjected to intense heat of about 
1,000 degrees Fahrenheit or over, for a continuous period will lose a part of the water 
taken up in crystallisation. This is known as dehydration, and when dehydration is 
complete the strength of the concrete is destroyed. 

Del. \ drat ion, however, is a very slow process, and will, even in the most seven' 
fire, only extend to the depth of one inch of the concrete, although cracks may extend 
further. Dehydrated material, being a poor conductor of heat and generally remain- 
ing in place for some time at least, it protects the mass of concrete from further 
dehydration. 

It is not good practice, as a general proposition, to use the same material for 
.structural duty and for resisting lire. The fire alone will give stresses enough for the 
material to resist without having to resist any structural load. 

If the quantity of concrete on the outside of a reinforced column or beam is 
increased so as to allow a loss of the material during" a fire without affecting the load- 
bearing quality of the structural member, the additional material added for fire resisting 
will participate in the load carrying, in spite of all that is done, and this would render 
it less able to resist a fire. 

Fuithermore, should the lire be so severe as to cause dehydration, cracks may 
extend bevond the dehydrated portion to the steel reinforcement, with obvious results, 
owing to the column or beam covering being an homogeneous material. 

The ideal way to protect a structural member would be to construct that member 
as a unit of sufficient strength to withstand all structural loads, and then to place the 
fire protective covering on separately. This would allow of dehydration without 
affecting the load-bearing quality of the member, and, also, should cracks occur it is 
probable that they would not extend further than the covering owing to its separate 
construction. 

For this reason, to ensure a first-class fire-resisting risk, a thickness of one inch 
of concrete on the outside of a structural member is, to my mind, sufficient for a 
separate fire protective covering for a reinforced member, while three inches should 
be regarded as necessarv if the fireproofing is incorporated with the material for the 
column itself. 

The above, however, should be regarded as a general statement, the covering 
necessarv being dependent upon the class of trade for which the building is to be used 
and the' likelihood or otherwise of a fire therein attaining a high temperature, and 
discretion should be used in specifying whenever an opportunity occurs, which I think 
will not be very frequent under existing conditions, owing to the extra cost involved 
bv separately protecting a reinforced member. 

It is my personal opinion that the rules applicable to buildings of fire-resisting 
construction" could, with advantage, be revised and extended, as also could the discounts 
allowed, particularly in regard to buildings of reinforced concrete construction. 

e ' ' '■ +9 



SEW WORKS IN CONCRETE. 



fCONC^TEl 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information -will be presented of neiv -works in course o/ 
construction or completed, and the examples selected 'will be from all parts of the •world. 
It is not the intention to describe these "works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea -which served as a basis 
for the design. — ED. 



THE PARKSVILLE CONCRETE DAM AND POWER PLANT. 

The accompanying illustrations show the Parksville concrete dam and power plant 
of the Eastern Tennessee Power Co. This installation, on the Ocoee River, at Parks- 

. Tennessee , with its 38,000 horse-power ultimate capacity and a distributing range 
of over 100 miles in every •direction, takes its place among the great water-power 
d jvelopments of the country. 

There are many interesting engineering features in its construction. Rising in 
the mountains of Northern Georgia, 
the Ocoee River flows through a 
region of heavy rainfall in a north- 
westerly direction to a point near 
Parksville, Tennessee, where it joins 
the Eiawassee, in its course draining 
an area of more than 600 sq. miles. 

At Parksville the mountains 
have been cut by Nature to form a 
deep and narrow gorge, above which 
the river flows for many miles 
through a broad and spacious basin 
a location well suited to the pur- 
poses of water-power development. 
Where the valley is narrowest the 
great Ocoee Dam now stands span- 
ning a gap of more than 800 ft. and 
filling the gorge to a height of 125 ft. 
from the river bed. The river, held 
captive in the valley above, forms a 
lake eight miles long, covering an 
ana of 3^ sq. miles in extent and 
containing 100,000 acre ft. of stored 
water. 

In order to accomplish this, 
[55,472 cu. yds. of concrete were 
place,] in the dam in exactly one 
year from the date of commencing. 

Tie- flam is built throughout of solid 

1 1 lopean concrete, 840 ft. long at 
the < resl , from 115 to 12- ft . thick 
at its base, with a spillway 362 ft. 

in length, capable of passing a flood 
of 45,000 CU. ft . -ea< h &e< ond. 

It may be slated that the pen- 

1 ks, through whi< h thai pori ion 

of the waiter utilised for power 

reaches the turbines, are tubelike 

cavities left in the masonrv of the ■,■ ,, ^ ,, 

I in-: Parksville Concrete Dam and Power Plant. 




5° 



'/, CONM KMICHONAl. 
A I NdlNl 1 l.'INti — , 



PARKSVILLE CONCRETE DAM- 



dam. The water enters these al a poinl aboul 30 ft. below the crest, thus permit 
OI1 l\ ihc top layer, about 20 ft. in thickness, to be used. 

The main turbine chambers are likewise located wholh within the dam. The 
powei house is situated immediate!} below the dam to the north ol the spillway, its 
substructure being an integral pari of the dam itself. The main building, [65 ft. long 




The Parks\ tlle Concrete Dam and Power Plant. 



and 35 ft. wide, contains the generating apparatus. Four main generating units and 
two ■exciter units are in operation, and the additional main unit for which provision was 
made in the original plans is now being installed. 

The large turbines, which are mounted on horizontal shafts and connected direct 
with the generators, are designed to produce 5,400 horse-power each when operating 



E 2 



s I 



NEW WORKS IN CONCRETE. 



[CQNCREXEJ 




j, CONM UUKTIONAl 

V UMC.lNhlk'lNC. — . 



ALLBNTOWN BRIDGE. 



al the rate oi 360 revolutions per minute undei a pressure head o\ 98 ft. 'I he g< nerators 
have .1 capacity ol 3,000 kilowatts and are operated al a voltage <>l 2,300. In the win j 
to the north of the main building are housed the transformers and high tension appa- 
ratus. The transformers, four in number, which are oil insulated and water cooled, 
increase the voltage from 2,300 to 66,000, al which the energ\ is carried over the tran 
mission lines. 

li is ol interesl to note thai from quarries in 1 ii< ■ mountain side just below the dam 
stone was loaded by steam shovels to the dump ears, hauled b\ donkey enj the 

crushei plant, and there reduced to the required sizes of both stone ; ■ n < i sand. The 
materials thus applied l>\ one process were then carried l>\ bell conveyors to the storage 
hins over the concrete mixers, into which they were fed by gravity. 

The cement was supplied to the mixers in a similar manner and the water from 
large storage tanks. From the mixers the concrete was loaded into buckets having a 
capacity of 2 cu. yds., hauled on flat cars to th<' dam, hoisted h\ derricks and dumped 
between the wooden forms to the place of its destination. 

ALLENTOWN BRIDGE. 

Our illustration shows one of the largest concrete viaducts recently erected in America. 
It is intended to carry the heavy inter-urban trains of the Lehigh Valley Transit Co., 
an inter-urban line running between Philadelphia and Allentown, and it is also to 
provide a highway toll crossing. 

The bridge crosses a valley about 125 ft. deep at its deepest part. 

Inclusive of approaches the bridge is 2,600 ft. long, the main part of which is made 
up of nine 120-ft. clear span arches and eighty 52^-ft. girder spans, arched for archi- 
tectural effect. It carries a 32-ft. roadway with two 7-ft. sidewalks. 

The chief engineer for this construction was Mr. W. \Y. Wysor, whilst the plans 
and specifications were prepared by Mr. B. H. Davis, of New York, who acted as 
consulting engineer during the work. 



:>:> 



NEW BOOKS. 



K3QNGEEXE1 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books which have appeared during the last feiv months. 



The Engineering Society of China. Report 
of the Special Committee on Reinforced 
Concrete. 

This society passed a resolution on 
December 20th, 1910, to appoint a special 
committee to enquire into the use of re- 
inforced concrete, and this report is issued 
as the result of the investigations. 

The tests that were conducted are not of 
universal interest, as all the materials 
employed were local and unobtainable in 
this country, and as the committee were 
hampered through lack of funds, the work 
done does not cover a very large field. 

The provision of a suitable testing plant 
was a matter of great difficulty, and the 
purchase by the Municipal Council of 
Shanghai of a compression testing 
machine was helpful, as permission was 
obtained to use this. The Municipal 
Council also assisted financially by making 
a grant to the society, and without this 
timely help from the Council practically 
nothing could have been carried out. 

The committee, in presenting the report, 
fully realise that a great deal still remains 
to be done, but it is hoped to continue the 
investigations at some future time. 

Three brands of cement, all of which 
are Chinese, were tested, and these were 
found to comply with the British standard 
specification in each ca.se. Six kinds of 
loc-d -and were tested, together with six 
varieties of local stone, and, generally 
Speaking, these were all found satisfac- 
tory, with the exception of the Soochow 
sands, which were shown to be inferior 
and not io ]><■ re< ommended. 

The reinforcement tested consisted of 
ordinary round and deformed bars, and 
these tests were conducted, by the permis- 



sion of the Chinese authorities, at the 
Shanghai Arsenal, the machine used being 
a single 1 - lever machine (Wickstead's 
Patent) manufactured by Buckton and 
Co., Leeds, and capable of exerting a pull 
of 50 tons and testing material having a 
breaking strength of 300 tons per sq. in. 

Concrete blocks were tested for compres- 
sion strength, 610 specimens being dealt 
with in all, and after these beams and 
slabs were considered. These beams and 
slabs were reinforced in various ways and 
with different amounts of metal, and the 
concrete was also varied. The preliminary 
tests consisted of four beams, and all these 
failed by destroying the bond between 
steel and concrete. Final tests were then 
conducted with three sets of sixteen beams, 
half being made with gravel and half with 
broken-stone concrete. It was found that 
in no case did the concrete reach its 
maximum resistance, and the failure in 
several cases indicated the necessitv of 
securing the bars at the ends. 

In addition to the description of the tests 
with the reinforced slabs, notes are added 
on the fire-resisting qualities of reinforced 
concrete, the question of making a re- 
inforced concrete structure impermeable 
to water, and the effect of electrolysis on 
metal embedded in cement concrete. Two 
appendices are given at the end of the 
report, the first of which is a specifica- 
tion for cement, and the second the 
certified analyses of the three different 
brands of cement that were used in the 

tests. 

Although the work done by the com- 
mittee refers exclusively to local mate- 
rials, the report is nevertheless interesting, 
and will be of value to engineers engaged 
in reinforced concrete work in China." 



54 



j CONM'PlRTIONAl! 
A-ENOlNhl VINO — , 



SANITARY FLOORS FOR 'Jill-: DAIRY BARN. 



POPULAR USES. 

Under this heading it is proposed from time to time to present particulars of the more 
popular uses to which concrete and reinforced concrete can be put t ast for instance m the 
construction ofhouses$ <.ott.nws.uuif.irn] buildings' Previous articles will be found in our 
: er, 1Q12, jnJ r anuary, M.m-h, Jutv, October and November of last ■ 





SANITARY FLOORS FOR THE DAIRY BARN. 
Method of Laying Concrete Floors with Farm Labour. 

1 1 is of the utmost importance to the farmer that his barn floors should l><- sanitary and 
so made thai they can be kepi clean without much trouble. Concrete floors lend them- 
selves admirably for this purpose. These floors arc easily laid, and their cosl i-> 




Sanitary Floor with Concrete Manger and Swinging Stanchions. 



small. The plan here described is for a barn in which the two rows of cows stand 
heels towards each other, with a driveway between. It can be easily modified to the 
opposite arrangement. Likewise the method is adaptable to both old and new barns. 

Planning and Grading the Floor. 

For average conditions lay out the stalls on 3 ft. 6 in. centres and 4 ft. 6 in. in 
length from 6-in. manger wall to drop gutter. The manger is 2 ft. 6 in. wide at the 
top and 2 ft. at the bottom, with one face sloping up to the feed-alley floor. The depth 
is 7 in., measured from the stanchion setting, and 8 in. from the alley floor. The feed 
alley is 4 ft. 6 in. wide. The drop gutter has a width of 18 in. ; it is 8 in. deep gauged 
from the stall floor, which is 2 in. higher than the 8 ft. driveway. For establishing 
grade lines a carpenter's spirit level (or a water level) and a chalk line are very helpful. 

To prevent any possibility of the floor settling, remove all manure before grading 
the surface of the earthen floor. Carefully tamp back the dirt around water pipes and 
the drains which carry waste water and liquid manure to the water-tight concrete 
manure pit. Do all filling as long as possible before building the concrete floor. As a 
foundation for the stall floors proper, place a 6-in. thickness of coarse broken stone or 
screened gravel to keep the floor from direct contact with the ground. Since the stall 
floors are of prime importance, it is well to make them first. During this operation 
the unpaved driveway and alleys can be used as working space. Then finish, in the 
order named, the feed alleys, the driveways, the mangers, and lastly the gutters. 

Mixing and Laying the Concrete. 

For the plan given, 5 ft. 6 in. from the centre line of the driveway stake on edge 
(and to line and grade) a 2 by 12 in. plank, to serve as a form for the stall floor 
at the gutter. Likewise set a similar board, 5 ft. distant, to mould the 6 in. manger 

55 



POPULAR USES. 



[CONCRETE] 



wall and stanchion setting. It must be remembered that the stall floor has a slope of 
i in. towards the gutter and that the stanchion setting rises 7 in. above the stall 
floor. Drainage for gutters and mangers will be provided by sloping their concrete 
bottoms. 

Proportion the concrete 1 bag of Portland cement to 2^ cub. ft. of sand and 5 cub. ft. 
of crushed rock, or 1 bag of cement to 5 cub. ft. of clean pit gravel. At one operation 



7^| 
v 



J& 5LO/=>£ 



+ -G 



s- . S'-o'. 




M^JtP^l 



/£' ' CROW At 



*-f ^.fylf a'- a- ^^ 



/r-6' 



Cross-Section of Concrete Dairy Barn Floor showing Usual Dimensions. 



lay the full 5 in. thickness of the stall floor and finish three stalls the same as one 
section of sidewalk. No surfacing mortar is needed. A wooden float is best for 
finishing the floor. A steel trowel yields too smooth a surface and such a finish should 
always be roughened by brushing with a stable broom. 

While the concrete of the three stalls is still soft, mould the stanchion setting (6 in. 
thick) upon it. As forms use the projecting 7-in. height of the 2 by 12-in. piece 
already in place and two 1 by 6-in. boards toe-nailed together so as to provide 
another 7-in. height and a bearing plate to rest on the green concrete. These forms 
may be made dish-shaped for swinging stanchions. Fill the forms with mushy wet 
concrete, trowel the surface, round the corners, and set the stanchion holders. Repeat 
the operation until all stall floors are completed. The feed alleys and driveway are 
easily built : they are merely rough-finished sidewalks. Place the waste-water outlets 
in the mangers at intervals of 28 ft. and give the bottom a slope of 1 in. towards each 
outlet for a distance of 14 ft. on each side of it. The drop gutters may be drained in 
like manner, or can be sloped slightly in one direction for their full length. For ease 
in cleaning, round all angles and corners (except at the bottom of the drop gutters) 
by applying a 1 to 2 cement-sand mortar immediately after removing the forms. 

Caring for Cattle and Floor. 

Regardless of the kind of floor, bedding of straw or litter is an absolute necessity : 
it keeps the COW clean and absorbs the valuable liquid manure. If the help cannot be 
depended on to bed the cows properly, it is advisable to use a removable wooden grating 
or platform. Cork bricks also give satisfactory results, but are somewhat expensive. 
They are set in a 2-in. depression in the floor and are held in position ion all sides by 
the concrete acting as a curb. 

With the proportions and thickness given above, 4 bags (1 barrel) of cement, 
10 cub. ft. of s;ind (say _ ; cub. yard), and 20 cub. ft. of crushed rock (about : ) cub. ward) 
will lay 45 to 50 scj. f 1 . of floor. 



5 6 



• .OONMkMRTIONAl 
V KNC.1M I KM NO ^, 



MEMORANDA 




Memoranda and News Items are presented under this heading, with occasional editorial 
comment. Authentic nexus "will be welcome. — ED. 



American Concrete Institute. — The eleventh annual Convention of the Institute 

will be held at the Auditorium Hotel, Chicago, 111., February 9-1 2th, 1915. This 
Convention will mark the completion of the tenth year of the existence of the Institute, 
and an especially interesting and profitable programme is being arranged. Some ol the 
subjects to be discussed are: concrete roads, sidewalks, and bridges; concrete and 
reinforced concrete tests and design; concrete in art and architecture; plant management 

and costs. 

The Institute has just issued its October-November Journal. 

Part I. covers Institute notes, with announcement of the summary of the 
programme of the above-mentioned Convention. 

Part II. covers the proceedings of the Institute, this issue containing: 

Report of the test of a reinforced concrete flat slab floor by W. A. Slater, showing 
a comparison between actual and design stresses. 

Report of the Committee on specifications and methods of tests for concrete 
materials, giving results of experiments conducted under the supervision of the 
Committee to determine the best form of concrete compression test piece and tests to 
obtain data to form a basis for standard specifications for sand, stone, etc. 

Paper on some comparative corrosion tests of plastered metal lath, by J. C. 
P-arson, of the Bureau of Standards, giving details of tests and observations on the 
weathering effect on mortar panels of various proportions and ingredients. 

Paper by Cloyd M. Chapman, giving data on lime putty and cream of lime, being 
the results of experiments to determine the necessary quantity of water to be added to 
hvdrated or quicklime to give putty or cream of standard consistency. The data given 
is of great assistance to all engineers and contractors using plaster. 

The Association of Consulting Engineers (Incorporated). — Vox some time past 
the Committee have had under consideration the advisability of issuing, for the guidance 
of the public and the profession, a scale setting out the usual professional fees, and the 
rules under which its members work. These have now been drawn up, and are 
available on application to the hon. secretary. 

The British Engineers' Association.— The following is a short extract from 
speech by Mr. Wilfrid Stokes, chairman of the Executive Committee of the Association, 
on the necessity for reconstructing those Government Departments which deal with 
foreign trade, by establishing a new Board of Industry :— At the present moment 
attention naturally turns to our foreign trade conditions and how they are and may be 
affected by the War. There is a general feeling of uneasiness in connection with our 
present position with regard to foreign markets. 

While it is universally acknowledged that the greatness of England depends upon 
her foreign trade, it is apparent that there is no adequate machinery provided by our 
Government Departments for properly extending and developing it. 



57 



MEMORANDA. [CQNCBETEJ 

It falls to the lot of tin Foreign Office and the Board of Trade to deal with this 
matter, but both these departm* nts are seriously hampered by the lack of funds and 
neither of them was ever constituted for this special purpose. 

Just as we have an Army and Navy with their experienced technical advisers to 
defend our country, so we should have bodies of trained men all over the world to 
defend our trade under equally qualified leaders. 

This trained force should be brought up with an intimate knowledge of our business 
requirements, and the leaders of it should be- well paid so as to attract men of marked 
capacity and ambition after they have given proof of these qualities in business b'fe. 

A paid council composed of the best business men of the country and representa- 
tives of the High Commissioners of our self-governing dependencies, the India Office, 
and the Agents-General of the Colonies, should be formed and should meet at intervals 
to decide upon the general policy to be followed. It should be the duty of some of the 
members of Council to visit foreign countries and our Colonies to> collect information 
at first hand. The head of this Council should be, ipso facto, a member of the Cabinet, 
and should be a permanent official chosen for his ability, and in receipt of a high salary. 
The Council should have a Parliamentary Secretary as its mouthpiece appointed by the 
Government in office, and the Department should be named the 4< Board of Industry." 

Numerous qualified Trade Commissioners should be appointed in our dependencies 
and Colonies, and in foreign countries, with adequate staffs and ample office accom- 
modation. The function of these Commissioners would be to promote the foreign trade 
of the Empire, thus relieving the Consuls of that portion of their work. 

Our Ambassadors and Ministers should be provided with ample funds to further 
British trade interests by legitimate means. 

The Commercial Attache service should offer a separate and distinct career and 
should be made sufficiently attractive to secure the right men. 

Owing to the fundamental character of these reforms, there is only one way of 
attaining them and that is by universal co-operation. 

The cost of this war will, of necessity, be very £*reat, so great indeed that its 
payment musl be spread over a very long term of years. If our foreign trade is bad in 
the future this burden will be hard to bear. It is thus our obvious duty, as a 
community, to extend and improve our foreign trade to the utmost by all legitimate 
means. 

By doing this we should hand on to posterity not only a heavy debt, but also a 
ready mean-- of meeting the liabilities which have been forced upon us by the war. 

An appeal is therefore made to .all business men to do their best to further the 
reforms outlined above. 

Lining Large Steel Coal Tank with Concrete. — As a preventive against the 
corrosive action of sulphur in coal and against abrasion, the Minnesota Steel Co. 
has lined a large circular steel coal tank at Dululh with concrete. The tank, which is 
approximately 55ft. in diameter and 40 ft. high, with a capacity of 2,100 tons of 
coal, is used in supplying coal to the steel company's coke plant. For furnishing coal 
for the ^,-iv producers of the open-hearth furnaces, thirty-three parabolic bunkers, 
approximately 20 fi. wide, 12 fi. deep, and 17 ft. long, are provided. The coke-oven 
bin- were lined with 5 in. of concrete and the producer bins with a 2-in. concrete lining. 
'lip i' in' in gun was used for the purpose 

Iron lu^s were provided ai numerous places around the inside of the tank'. To 
1 1 1 ' ~* • vertical rods were securely wired in horizontal bands. The wire mesh was held 
away from the steel by a distance of 'l in. Gunite was then applied. The first layer 
was shot through the mesh; ii served to hold the wire cloth in place and covered and 
protected the steel plate. The second layer, bringing the coating to a total thickness of 
5 in., was then applied. 

Tin- gunite applied consisted of a 1 13 mix of Portland cemenl and sand. It was 
shot through the hose by th< gun with an air pressure of from 40 to 60 lb. Immediately 
before emerging from the nozzle the dry mixture was hydrated, the water coming 
through a separate and smaller hose the quantity of water was under the control of 
the operator. The Engineering Record. 

5« 



\j CONM Pile! IUNAI 
1A I NdlNl 1 K'1N(. — , 



MEMORANDA 



Concrete for Purifier House at the Poole Gas Works. In i n < < ni in 
7 he Journal <»,' Gas Lighting gave .1 shorl account, with illustrations of th< 
purifier house erected for the above Gas Co. The purifier house is ol i<in!<Hi< I 
concrete on 1 1 1 «* - " ll\ rib ' system, and as the ground in the neighbourhood is verj 
soft, the whole installation is " floated " on a reinforced concrete rafl 2 li . 6 in. thick, 
thus saving much expense in excavation. The total distributed load is 750 tons, and 
no movement has taken place since the raft has been loaded. 

Cathedral in Reinforced Concrete at Georgetown, Demeran;. li has been 
decided to build the new Roman Catholic Cathedral at Georgetown in reinforced 
concrete on the Considere system. The construction is to be as lighi as possible ; there 
will be .1 concr< te raft over the whole area of the building so as to distribute the weight 
evenlj over the whole ground covered. 

Concrete Vaults. — Some of the American banking companies have recently 
adopted concrete for the construction of the bank vaults. The concrete is heavil) 
reinforced and otherwise protected by electrical safet) devices. The Depositors' and 
State Savings Bank in Chicago has a 2-storey vault, 20 ft. high and iS ft. by 20 ft. in 
plan. The floor is a 12-in. slab of concrete reinforced with ^-in. rods placed on 6-in. 
centres in both directions, and near the centre of the slab additional protection is 
provided by steel rails laid at close intervals. Similar protection is provided in the 
iS-in. walls by the ;-in. reinforcing rods running in both directions. The roof is a 
10-in. slab built like the floor. The Home Hank and Trust Co., also of Chicago, have 
also constructed a vault oi reinforced concrete. It isj (15 ft. long, 14 ft. wide, and 
1 1 ft. high. 

Concrete Lining for Steel Hull of a Steam Launch. — In the Engineering 
Sews, Mr. Horace M. Marshall, U.S. Engineer, Vkksburg, Miss., gives an interesting 
account of how the steel hull of a steam launch was preserved after it had been in 
use for thirteen years. In the first instance the hull was lined with cinder concrete 
reinforc<d with chicken wire. The hull was 65^ ft. long, io£ ft. beam, and 4 ft. deep 
amidships; the plating was of soft steel 4^ lb. per sq. ft.; the draft was 20 in. to 
24 in., according to load; and the wheel 30 in. in diameter. The wheel revolves 
in a tunnel, and when the boat is not under way only about two-thirds is below the 
water-line, but it is submerged when running; the water rises and fills the tunnel. 
When the boat was thirteen years old " pin-holes " developed all over the plating, 
and the plates were so rusted as to render the boat dangerous. 

This state of affairs was met by a concrete lining. The hull inside was thoroughly 
scraped and cleaned. Chicken wire was spread over the ribs, and the cinder concrete 
rammed down through the mesh all over the bottom of the boat, extending well up 
on the sides above the water-line. The lining was from 4 in. to 5 in. thick at the 
keel and thinned towards the sides of the hull. The added weight was 8,000 lb., which 
increased the draught 3 in. to 6 in. The boat now worked satisfactorily for some 
three or four years, when the steel plates had grown so thin that it was feared the 
concrete would drop out ; otherwise the vessel was in good condition. 

This new difficulty was met bv the application of a new steel skin or shell, which, 
however, necessitated the removal of most of the concrete, leaving only the concrete 
which was under the engine bed. 

ENQUIRY. 

A subscriber writes as follows: — " For a number of years I have been a subscriber 
to your magazine and would therefore ask you to let me know the best way of making 
an expansion joint in reinforced concrete. As a rule, I take it, expansion joints are 
not required, but it might be desirable to have such — for instance, in long trestle bridges, 
jetties, or reinforced concrete wharfs. If you published drawings and particulars in 
your magazine others might find it interesting, as most textbooks that I have come 
across have remarkably little to say on the subject in general. 

Reply. 
Expansion Joints. — Expansion joints are only necessary when the area of concrete 
is large, or there is a large uninterrupted length such as a bridge or wall. The object 
of the joint is naturally to prevent cracks occurring, and it is really a means of 

59 



MEMORANDA 



[CONCRET E] 



practically putting the crack in a selected position when executing the work, in 
preference to running the risk of possibly several cracks which would be unsightly. 
The exact method of forming the joint will vary according to the circumstances of 
each case, but generally it is formed by inserting a board, say, i in. wide, or less, as 
the case may be, ami filling in the concrete on both sides. This board is withdrawn 
just as the concrete is setting and the space is filled in with sand or asphalt, or any 
matt-rial which will not hi- too rigid. Sometimes tarred felt or several thicknesses of 
tarred paper are put in to cut the concrete into sections, and these are allowed to 
remain. In any case, cue must be taken thai the space is not left in such a manner 
that water can penetrate to the reinforcement and cause rusting and decay. In a 
reinforced concrete over-bridge, Ashton-under-Lyne, where there are large parallel 
girders of thr< e spans, the girders are cut over each intermediate support, and a space 
of Itj in. is left between the ends of the adjoining girders to allow for expansion. In 
the reinforced concrete retaining wall at the Royal Automobile Club, which .is 228 ft. 
long, no allowance in the way of joints is made for expansion, but sufficient distribution 
rods are put in to take up the stress, and the cracks are then so distributed and fine 
as to be invisible to the naked eve. 

A. L. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum J-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 



The VICTORIA 

is built to last 

WRITE FOR CATALOGUE No. 29. 



THE 

T. L. SMITH Co. 

13, Victoria Street, S.W. 



60 



Please mention this Journal ii)hen writing. 



CONCRETE 

AND 

CONfiTRUCnCfNAL ENGINEERING 



Volume X., No. 2. London, February, L915. 

EDITORIAL NOTES. 



CONCRETE AND REINFORCED CONCRETE IN MUNICIPAL WORKS. 

The excellent paper read by Mr. H. J. Tingle, M.Inst.C.E., before the Concrete 
Institute, at their meeting last month, was particularly appropriate just at 
this time, when we arc about to consider the re-planning and re-building o\ 

the cities and towns of Belgium, with their municipal works, which have been 

so ruthlessly destroyed by the invader. 

Unfortunately, the title of Mr. Tingle's paper did not do justice to it. 
" The Application of Concrete in Modern Sanitation " was a title which 
scarcely gave one the impression that the author intended in this to deal with 
concrete and reinforced concrete sewers, reservoirs, sewage tanks, the manu- 
facture of reinforced pipes, reinforced-concrete manholes, the cause ol the 
failure of certain reservoirs, sewer outfalls, hydrolytic tanks in reinforced 
concrete, and many other important subjects. If the title had been "The Use 
of Reinforced-Concrete in Municipal Works," it would have been more- 
appropriate. 

As to the paper itself, Mr. Tingle certainly summarised in a most interest- 
ing- manner a great deal of information, and one agrees with much that was 
included in the paper; but if one might offer a word of criticism, one would say 
the author attempted to include in one paper what could not be satis- 
factorily dealt with in half a dozen. Any of the subjects referred to 
would have been suflicient for one paper, and we trust he will be per- 
suaded to develop the individual chapters. With regard to the use of 
concrete sewer tubes, undoubtedly these can be strongly recommended, but 
experience has shown that it is always desirable to haunch them up with con- 
crete, as shown in Fig. i of the paper; and they should never be laid in trench, 
as shown in the author's Fig. 9, without this concrete support, otherwise 
failure is invited. The collapse of concrete tubes through the omission of this 
safeguard would be a poor recommendation for the use of these tubes in sewer 
construction. If this precaution is taken, concrete tubes are admirable for 
sewers. 

As to the reservoir which Mr. Ting-le informs us failed, we think the design 
was certainly fault}-, and that it would have been remarkable if the structure 
had not failed. 

It is unfortunate that in selecting typical examples of the use of concrete 
and reinforced concrete in municipal engineering works, the author did not 
give us better samples of works constructed in these materials, but as already 

61 



CONCRETE IN MUNICIPAL WORKS. 



[CONCRET E] 



indicated, t;> cover the ground fully, a series of lectures would be necessary, 
Concrete and reinforced concrete arc undoubtedly eminently suitable for most 
municipal works, and excellent examples of their use in all kinds of such work 
may be found in this country and in America. Many instances of their use in this 
direction were given recently in a public lecture at the University of London. 

As to temperature cracks in reservoir walls, these will occur unless expan- 
sion joints are put in or additional reinforcement to prevent them. 

In conclusion, we would say that this paper, which was one of the best 
presented at the Institute, produced a very interesting- discussion, and the 
general opinion was that provided the}' are properly designed, and the work 
is carried out in a workmanlike manner, concrete and reinforced concrete 
can be strongly recommended for municipal works. 

REINFORCED CONCRETE IN EARTHQUAKE DISTRICTS. 

It is reported in the daily Press that in connection with the earthquake 
in Avezzano a house said to be built of reinforced concrete withstood the 
shock and remained undamaged, and it is stated that it is the only one in the 
town which was left complete. We reproduce the accompanying- illustration by 
courtesy of the Daily Mirror. We hope to be able to obtain further particulars 
and to publish them in a future issue. 




i TO BE "i Hi [NFOR4 ED Com RETE, which wn HSTOOD EARTHQUAKE Siidck AT AVEZZANO. 



\k 



CDroikuirnoNAT 

pV(ilNM-WlN(. — . 



REINFORCED CONCRETE CAISSONS, 




- 



REINFORCED 

CONCRETE 

CAISSONS AT 

SUNDERLAND 

DOCKS. 



We are indebted to Mr. Wm. 
Simpson, M.Inst.C- E., Engineer-in- 
Chiefto the Rimer Wear Commissioners, 
Sunderland, for the following interest - 
ing particulars and illustrations. ED. 



The River Wear Commis- 
sioners, the Port of Sunder- 
land Authority, have just 
constructed and launched at 
Sunderland two reinforced 
concrete caissons required for 
dock improvement works 
which have many interesting' and novel features. 

Each caisson is of box form 26 ft. square, 23J ft. high, and is com- 
pletely covered in on top {Figs. 1 and 5). A shaft, 3 ft. diameter, rises 
to a height of 11 ft. above the level of the roof, and is the means of access 
to the interior of the caisson. The bottom, walls, and roof of the caisson 
are stiffened with beams, and strutted with internal bracings. This is 
necessary, as the empty caisson has to sustain a maximum head of 36 ft. 
of water when sunk in position. 

The caisson is required to carry a masonry superstructure, which will 
be built in the dry while the caisson is afloat. This top load will even- 
tually sink the caisson in place, and it has been so arranged that when 
the caisson has grounded on the prepared base the top of the superstruc- 
ture will stand clear above the ordinary water level of 34 ft., measured 
from the dock bottom. The caisson will then be filled up solid with 
concrete, passed through the shaft in the dry, and the remainder of the 
superstructure completed. In this way the whole of the work will have 
been built and hearted in the dry, thus ensuring good results in the 
quality of the work. 

Grout pipes are provided, leading from the bottom to the top of the 



6} 



REINFORCED CONCRETE CAISSONS. 



[CONCRETE 



caisson, so that a solid bearing can be formed between the prepared base 
and the bottom of the caisson. 




Fig. 2. View of Bottom of Caisson with Steel Reinforcement of Floor and Stiffening Beams in Place. 




l''H. 3. Vi< w of Bottom of Caisson with Concrete Ploor being i.ut in Place. 
Reinforced Concrete Caissons, Sunderland Docks. 

'J he caissons Iiave been built, one behind the other, on a flat foreshore 
of the River Wear, and were launched from ways, h.'iving a commencing 

64 



g 



1-ONMPlK-HONAlJ 
KNir.lNKKUlNt. —J 



REINFORCl-I) CONCRETE CAISSONS. 



-> rrsrse 




C/POS-S SfCT/OA/ 




Fig. 4. Sectional Plan. 
Reinforced Concrete Caissons, Sunderland Docks. 



B 2 



65 



REINFORCED CONCRETE CAISSONS. 



[CONCRETE 



gradient of i in 15 and terminating at 1 in 12. The launching ways are 
three in number, and as the launching draft of each caisson is 14J ft., 
these ways had to be carried a distance of over 200 ft. from the site before 
the requisite depth of water was obtained. The caissons were first sup- 
ported on building ways, placed between the launching ways, and just 
before launching the weight was transferred from the building to the 
launching ways by placing sliding cradles under each caisson, and block- 
ing and wedging them up to the caisson bottom. The blocks and wedges 
of the building ways were then knocked out, and the caisson rested its 
entire launching weight of 300 tons on the sliding cradles. 




F\ti. 5. View of Top of Caisson with Steel Reinforcement of Roof and Strengthening Beams being put in Place. 
Reinforced Concrete Caissons, Sunderland Docks. 

'I he caissons were constructed of concrete in the proportions of 
2§ cubic ft. granite chips to pass f-in. mesh, 2§ cubic ft. granite chips to 
pass J-in. mesh, 2§ cubic ft. sand, and 2 cubic ft. cement, making 10 cubic 
ft., or 4 to 1. This concrete was found to be 142 lb. per cubic ft. by 
actual weigh 1 after being mixed and dried. The concrete was placed in 
position between timber shutters, 2 in. thick, and about 6 ft. in height. 
'I hese were shored in position off scaffolding which completely surrounded 
th< caissons. 

The concrete was mixed on the site by a "Smith " mixer, and dis- 
tributed by means of limber spouts to the various points. As the heights 
of the walls increased, the mixed concrete was hoisted by a crane to plat- 
forms placed al suitable heights. The timber moulds and shutters were 
used alternately for each caisson, so that their construction proceeded 
simultaneously. 

66 



j r l'ONMLMI( I IUN\r 
* v IJsK.lNKKWlM. — 



REINFORCED CONCRETE CAISSONS. 



When launched, the caissons floated practically al the calculated 
draft, and were quite watertight. 

Th< caissons have been built <>n the Con side re system l>\ the Rivei 
Wear Commissioners' own workmen, to the designs and under the super- 
vision of Mr. Wm. Simpson, M.Inst.C.E., Engineer-in-Chief to the River 
Wear Commissioners, Sunderland. 

The accompanying photographs show the caissons under construc- 
tion and in course ol launching and being lowed to the site of the works 
in the docks (frontispiece). 




Fi^. 6. View of Caisson in Course of Launching from the Ways. 
Rkinforced Concrete Caissons, Sunderland Docks. 



6; 



EWART S. ANDREWS. 



IQQNCBEXEJ 




PROBLEMS IN THE THEORY OF 
CONSTRUCTION. 

COLUMN BENDING 

MOMENTS IN FRAME 

CONSTRUCTION 

(Conclusion.) 



H 



By EWART S. ANDREWS, B.Sc.Eng.(LoncL). 

This article is continued from page lb in our last issue, — ED. 



We now come to the consideration of a continuous beam of two equal spans, each 
carrying a uniformly distributed load but of different intensities, the beam being 
rigidly connected to one or more of the columns. 

Case I. Neglecting the Stiffness of the Columns. — If we neglect the effect of 
the stiffness of the columns upon the slope of the beam, we can investigate the bending 
moments and slopes as follows : — 

Referring to Fig. 7, in which w } and w 2 are the intensities of the loads on the spans 
1, 2; 2, 3 respectively, \a2, 263 
are the " free bending-moment 
diagrams," i.e., those which would 
occur if the beam were not con- 
tinuous, and lc3 is the reverse 
bending-moment diagram caused 
by the continuity, the resultant 
diagrams being the difference 
between the two as shown shaded 
in the figure. 

Treating the B.M. diagrams 
as imaginary loads, as before, we 
find the slopes by calculating the 
imaginary reactions. 

The are i of the parabola 1^2 



P. = ^ 



12 



3 8 

The area of the parabola 2&3 
__p _ 2 w./ J yl _w,i l 
- 3' 8 12* 




Fig. 7. 



The area of the A U2 = A3c2 = P :i = Ii., ; this acts through the centroid of the 

■A, i.e.. at a distance from 2. 

3 

I h<:n if r„ /%, /-; are the imaginary reactions at 1, 2, 3 we have by taking moments 

about 3, for the right-hand span, and calling clockwise moments positive*, 



63 



k^fAMViNf?^ COLUMN BENDING MOMENTS, 



} i i 

, ../ = /> . - .",. 
i 

I: . I u ./' 
24 

,.,.. r, x__*. (1) 



Similarly for the span L, 2 we have by taking moments about 1 

r '' 24 " 3 
3 " 24 "" 24 



(2) 



„ (tc^ + trJ/' 

/. t '.. B, = i — s a (3) 

16 



patting this result in either of equations (2) or (3) we get 

(w,—w 9 )l 3 



<4) 



48 
Knowing the value of 75, we might have reasoned in this way: r,= area of parabola 



lal — ~ area of Alc2. 
3 



= P <- 2 



24 3V II 



24 3V 16 /2 



■ 24 48 

_(te , 1 — a0 /! 



Similarly r 1 = : — — 



48 

2 3 



24 96 

_ (3tc'| — zepr* 
96 



(5) 



, P { P., 

and r 8 =— - — — 

3 2 

_ (wi+te; 2 )Z 3 _W 3 
96 24 

_ (w } — 3te> g )/ 3 

~96~^ 

If therefore /^is the moment of inertia of the beam, we have 

1 96E/ B 

= ( ^i~^ ^Z' 
48EI B 

_xc , 1 — 3tc , ,i/ i 
;i ~96EI B 



(6) 

(7) 
(8) 
(9) 



69 



EWART S. ANDREWS. 



(CONCRETE) 



But if B D \s the bending moment at the top of the column we have previously shown that 

kEl c e 



B D = 



Bdi — 



fe(3w,-tt-,)Z 2 .U C .E 



9bE.I B .h 
kiZw^—w^l 2 



Bm — 



96s, 



48s 2 

— k(3u> 2 — W])l 2 



Bdh 



96s, 



(10) 
(11) 
(12) 



As B D1 will always come less than B m , assuming that w l is greater than w 2 , we will 
not consider it further, and we regard equations (10) and (11) as giving the column 
bending moments for the exterior and interior columns respectively. 

In the common case in which the columns are fixed at the ends, A' = 4 giving the 
results: — 

(5wj —v\>)l~ 



B.M. at top of exterior column = 



B.M. 



interior 



24s, 
(to;, — w.,)l- 
12s, 



(13) 



:i4) 



Reaction on Columns. — Since the reaction at the end of a beam is given by the 
slope of the B.M. curve and the effect of continuity is to decrease the slope 

of the B.M. curve at the end 1 by an amount 2 " the reaction at 1 for the ordinary 



/ 



r B 

case ot non-contmuity will be diminished by an amount equal to — * because B l = 0. 

I 



.'. /?, 



_w l l_B. i 

2 " I 

~Y~ 16Z 

7w } l w.,l 
16 16 



[from (3)1 



Similarly 2? 3 = ^_^ 
16 16 



And since R { +R 2 +R 3 must be equal to the total load (w x -\- w 2 )l, we have 



R< 



^(w^ + Wjj)/ 
8 



(15) 
(16) 

(17) 



We may also write R, = wJ I "4 I 2 -^ 

2 2 I 



h 



30' 



-.+ 



3 



30' 



f A > > } ) r i i / > 7 / ii i / V/ > > / i f i I )))))?) ft >') 



Numerical Example. — We are 
now in a position to illustrate- our 
results as far as we have gone up to 
the present. Take the case illustrated 
in Fig. 8, the main beams being 15 ft. 
apart. The dead load may be taken 
as 80 lbs. per sq. ft. and the super load 
as 200 lbs. per sq. ft. 

Then for the left span loaded and the right unloaded we have w, -280 X 15=4,200, 
W 2 = 80 X 15 = 1,200 lb «. per ft. run. The maximum bending moment occur when boih 

70 



Fig 



' c^CCrvJTUTJCTIONAi: 



COLUMN HUN DING MOMFNTS. 



Section modulus required 



spans are loaded and is equal to' 11 "'.' °° ' ' M \ ' ' l - 5,670,OOOin. lb .and taking 

8 S 

B safe stress of 16,000 lbs. per so. in. we have : — 

5.(>7<>.<inn 
H>.()()() 
= 354*4 in." 
A compound girder composed of two H in. X o-in. X 4o-lb. I beams and plates to 
make 14 in. X 1 \ in. in each flange will give a modulus of 353"3 and a moment oi inertia 
of 3.020 in.' which will do well. 

Now consider the centre columns; w'.ien both spans are fully loaded, the load on 
the central column = g X 8,400 X 30= 157,500 lbs. = 70 - 3 tons. A 14-in. X 6-in. X 57 lb. 
I beam (/ t . = 532'9) will just carry this by the L.C.C. formula for fixed ends, and in the 
usual method of designing without taking account of the bending stresses in the column, 
this section would be regarded as amply strong. It will be best to arrange this with its 
long axis parallel to the beam, so as to carry the bending stresses better. 

The outside columns will only carry T :, rr x 70"3 = 21'9 tons. A 6-in. X 5 -in. X 25 -lb. 
I beam [7 c = 43'6l] will carry this. 

Now take the case of the left-hand span only covered with the live load. Then the 
load on the centre column = §(4,200+ 1,200)30 = 45"2 tons. 

[wi~ w t )l 
1 2s, 



By equation (14) the bending moment at the top of the interior column 



In our case 



s.,= 



_/ B ./i_3,020xi0 = 



Ic.l 532-9X30 



= 1-9 approx. 



i ,3 i 000X30X30X12_ 1|42a000 in ., bs . appri x . 



Bending stress 



12X1-9 
B D _ 1,420,000 
532-9 532-9 



X7 



= 18,700 lbs. per sq. in. 
This is more than the safe stress apart from the direct stress as a column and., 
unless our direct method of calculations is far from the truth, the column is not 
sufficiently strong. If the bending moment on the exterior column be calculated by 
equation (13), that column will be found to be more highly stressed still. 

Case II. Allowing for Stiffness of Central Column but neglecting that oj 
Exterior Columns. — In this case we allow for the stiffness of the central column but 
neglect that of the exterior columns ; for the purpose of finding the bending moment on 
the central column this is equivalent to assuming that the connection of the beam to the 

columns 1 and 3 does not alter the 
slope of the beam at the ends compared 
with the slopes which would occur if 
the ends merely rested upon supports. 

Fig. 9 shows the resultant B.M. 
diagram for the beam. There is a 
sudden change in the reverse B.M. 
diagram due to the bending moment 
B D , taken by the central column. Con- 
sidering the span 2, 3, we have by moments about 3 for finding the imaginary 
reactions, as before, 




Fig. 9. 



7 BJ21 
r.,l = —r- 



W 9 l 4 



(18) 



2.3 



24 



7 1 



EWART S. ANDREWS. 



CTCEET^ 



and considering the span 1, 2 and taking moments about 1 we get 



2+ V 



B,+B D , \m 



2~H 



i.e., 



or 



2B,+B D ,_ {w, + w.M' i 



24 



B ={ k\ + u\M 2 B D , 
16 " 2 



but 



I 48 6 24 

_ {u\ — w.)J- B^ 
48 d" 

>j = ElB0 = JjJ fl 
I I ll c , 

s 2 B Dl _ (t^i — u?,)7 2 _ B^ 
~D~ 



R .__kEI c .,0 



(19) 



(20) 



(21; 



B d ., _ s 2 Bq. j 

k ' k 



B 



»(H)= 



k 48 

1\ _ (^i~^ 2 )Z 2 
48 
(w 1 — w 2 )l i 

48 (r + -) 

\k 6/ 

_ k(w 1 — w 2 )l' J 
~ 8(6s.,+k) 



(22) 



Taking the values of k pre- 
viously given for the standard 
cases 1 to 4, we get the values 
which are plotted in Fig. 10. 

To find the total reverse B.M. 
B,).,-tB., on the beam, we have 
from equation (20) 

Total reverse B.M. = 

B Dj + B, = B D ,+ ^i+W* 2 gz» 



16 

— RlH i (Wi + W 2 )l 2 

" 2 id' 



(23) 



To draw the B.M. diagram, 
therefore, we set up 2c, Fig. 9, 

canal rn ( wi + w .Jl* /«. 

equal to — — -= — (the mean 

ID 
height of the two parabolas), this 
being the same as when the stiff- 
ness of the centre column is neg- 
lected; we then look up from 
Fig. 10 the value of B h . for the 
given method of fixing the ends 
and Bet down and up ce, cd equal 

to j 1 and complete the diagram 

as shown. 

72 




o t 

Stiffness coe 



>ffr-A. 



Lower end of column fixed. 
., hinged. 

slopes equally in opposite direction. 
• • ii n .• ,, same 

Fig. 10. 



[^t^SiyjiS^n COLUMN BENDING MOMENTS, 



To find the B.M. i»n exterior columns, say I, we have by momenta aboul 2, 

, w£ 4 _(B, I />'„.,) / 
24 2. ' s 

I k 24 6/ 

24 6/ 12/ 

2 1 o/ 1 _7 

. s x B Dx = ( 3 Wi— «;,)/' Bo, 

' " A- 96 12/ 

From the values of Bdj given in /^/'g. 10 B th can be found similarly, 



SiB Di {w x — Zw.>)t 2 B 



/>, 



h 96 + 12/ (25) 

Reaction on columns. — -The reaction on the centre column is given by 

*k-(f4?)».+ ad j 5 *+f' 

-(t)+?(**¥) 

..ala+^-^a,^ [from(20) ] 

The reaction on the centre column will therefore be the same as before. 
On the other columns we have 

Wyl B Di +B, 



#1= 



2 / 

_w l l_ (B Ds +B i ) _B D$ 

2 I 2/ 

_ zvi[ __ (u'| + w 2 )Z B D ., 

~ 2 16 ~~2T 

_ (7w l — w.>)l __B D2 
16 " 2/ 



[from (20)1 



This is the previous value minus — — , and R< will come equal to the previous value 

plus — ^ ; the effect therefore of the stiffness of the interior column is to take a slight 

amount of load off the more heavily loaded exterior column and to transfer it to the 
other side. 

Numerical example. — Taking the same numerical example as before we have in 
this case 

r> _k(w l — W 2 )l 2 _ 4(w l — U , 2 )l 2 

D ~ 8(6s + k) 8(11*4 + 4) 
= 3,000X30X30X12 ^ 

2X15'4 

.". Bending stress = 1, 050,00 ° X 7 = 13.800 lbs. per sq. in. 
5 532*9 

This is somewhat less than before, but still very serious ; this justifies our statement 
that the assumptions involved in the case (1) will err on the side of safety. 

73 



EWART S. ANDREWS. 



ICDMCRETEJ 



Case III. Allowing for stiffness in all the columns, but taking tlie tico exterior 
columns as of the same stiffness and method of fixing. This case leads us into more 
troublesome expressions, but can 
be investigated as follows : — Fig. 1 1 
illustrates the resulting B.M. dia- 
gram. 

Take first the first span and ^ ir ? 

consider the reverse B.M. diagrams , I 3 

as divided into two triangles, we 
have : — 

Taking moments about 1, 

r/ _zo,7 4 B.f B Dl l 2 




Fig. 11. 



24 

lW _«V 4 Bd' 2 B Dl l 2 

All ' 

24 6 3 



(26) 



(27) 



Dividing (27) by 2 and subtracting from (26) and dividing through by I 2 we get 
after simplifying 

wj 2 4r.,,2r l 



B, 

12 Z Z 

Patting this in (26) and simplifying we have 

r> _w 1 Z 2 ,2r.> 4r, 

Next considering the second span and reversing signs as before we have 

rl _-wX + B.X' B D .f 

2 24 3 6 
rl - -w 2 l' BJ' + B D f 

3 24 6 3 
Treating these in the same way as (26) and (27) we get 

w.,l 2 ■ 4r a 2r 3 
Z " 



B 2 = 



12 



/ 



Bd 



_ w./ 2 2r.> ,4r ;{ 

"l2~""T"T 



We next have the three relations 



B 



D] 



SjZ 



B D , = B,-B,= 



kr.j 
s~l 



From (29) and (34) 



#03= ~= -* (because .s, = .s. { ) 

.s- :j Z SjZ 

for, _ WjZ 2 | 2rj _ 4fj 

-s ,7 " 12 ~Z T 



I l*. / 12 / 
Similarly from (33) and (36) 

rifk+A- w 2 l* 2r 2 

/ Vs, / 12 Z 

Putting (28) and (32) in (35) we have 

Ur, _{u\ — w 2 )l 2 _ Hr. t , 2/-, , 2r, 
s 2 Z 12 III 

74 



(28) 

(29) 

(30) 
(31) 

(32) 
(33) 

(34) 
(35) 
(36) 

(37) 
(38) 

(39) 



rTTooN.vi-pui'noNAi.t 



COLUMN BENDING MOMENTS. 



2a ./ 



+ 



Putting results (37) aad (JS) in this we have 

At. [wj u-.)/' 8r, i ->,/'"' + _ h 

*T i 2 i ,^ M) ,g +4 ) ,15+4)" ig+4) 

r. "•' 1-8 „ H J (w,-»,)*' fl I ,' ) 

'•"■ ' r (I-+ 4 )j i2 I *- +4 t 

Simplifying and multiplying through by (- I 4j 

? { ( i +8) g i+4) _ 8 }Jk^i'g +4+2 ) 

«) 

12 1 (i +8 Xi ++ )- 8 



rj _ [w l — w t )l* 



12 



(6*,+fc)*> 



( (8s,+*)(4s 1 + *)-8s,s s I 



from (35) 



B»,= 



A';%_(w, — k\)1' 



k(6s x + k) 



s,l 12 I 8s 1 +Jfe)(4s, + /t)-8i-,.s i 

We will also find an expression for B Dl . 
From equation (37) 



(40) 
(41) 



l\s x ) 12 / 

and t = , — 

/ & 

■ N H ir"i2" + T 



(42) 



'" 2 having been found by equation (40) the value of B Dl can thus be found readily 

and B Di can be found similarly from equation (39). 

Numerical Example. — We can now find the value of the B.M. on the centre 
column for the numerical example that we have already considered. We have s, = l'9 
_3,0204-10. 



as before and 



4361 X30 



23 nearly, also & = 4 

(w i --tt07* < 4(138 + 4) ) 

Di 12 j(15'2 + 4)(92 + 4)-350l 



3 ,000 x 30 x 30 x 1 2 
12 



X*38 



= 1,030,000 in. -lbs. nearly. 
This is not appreciably different from the previous case in which we neglected the 
stiffness of the exterior columns. Suppose that the exterior columns were more stiff. 
say that their moment of inertia were half that of the interior column, we should then 
have s, = 3-8 and 

_(w,-ug/ 2 ! 4(22-8 + 4) \ 



B Di 



12 ((15-2 + 4)(15-2 + 4)-57-8) 

_ 3,000 X30X30X12 x 34y 

12 
= 930.000 in.-lbs. nearly. 



75 



EWART S. ANDREWS. 10QNCKETE] 

In the extreme case in which the exterior columns are infinitely stiff we have s^O 

and equation (41) gives Bd2=~-±- — -f— - 

12(8s 2 -r*) 

This corresponds to the case in which the extreme ends of the beam are fixed or 

" built-in. - ' 

In the case in which the column extends above the beam as well as below we may 

replace — in the various equations by — + b where the suffixes a, b indicate the quantities 
s s a s b 

for the columns above and below the beam respectively. 

The above treatment will, we think, demonstrate that there is considerable algebraic 
complexity involved in a rigorous treatment for the various conditions that may arise 
in practice, but that some such treatment is very necessary if high bending stresses in 
the columns are to be adequately met. 

If designers are convinced of the importance of the problem it should not be a 
matter of very great difficulty to devise rules that are simple to apply and sufficiently 
accurate to ensure adequate resistance against the bending stresses. 



76 



j.ODNMVUC-HONAl 




REINFORCED CONCRETE BUILDING, CI IK A( 






-A'^*^w^t 



A REINFORCED CONCRETE 

BUILDING FOR THE 
FORD MOTOR CO., CHICAGO. 



An interesting example of Reinforced Concrete construction is the neiv building for the 
Ford Motor Co., Chicago. We are indebted to our contemporary, " Engineering Neivs," 
U.S.A., for the description and illustrations here given. — ED. 



The new assembling- and service building- for the automobile business of the 
Ford Motor Co., at Chicago, presents some unusual and interesting- features 
in its design. The building has a 164-ft. front on 39th Street and extends south 
on Wabash Ave. 232 ft., with a provision for a further extension to a length 
of 460 ft. It is six stories hig-h, without basement. The building has 
rein forced-concrete columns, floors and roof. Except on the alley side, no out- 
side concrete is exposed, the exterior being of brick, terra-cotta and glass. 
The proportion of window area is large, in accordance with modern factory 
construction, and makes up about fx) per cent, of the exterior. 

The building- rests on a deep bed of sand. As the property is surrounded 
on three sides by streets and on one side by an alley, there is little danger of 
the foundations being- undermined by adjacent excavations. The foundations 
are all spread footings designed for a soil pressure of 3,500 lb. per sq. ft., 
including- the percentage of the live-load required by the Chicag-o building- code. 
The footing's under the wall columns on the street sides form a continuous 
g-irder 5 ft. 6 in. deep and from 7 ft. 4 in. to 8 ft. wide, Fig. 1. The widened 
portion (section B B) is to carry two intermediate columns one story high. The 
top of the footing is 15 in. below the first floor. 

The column foundations on the alley side and also at the south end of the 
building are simple spread footings. The typical exterior footings are 
14 ft. 3 in. square. Between the column footings on the alley side a 12-in. 
curtain wall of concrete was built for a depth of 3 ft. 9 in. below and 3 ft. 6 in. 
above the first-floor line. The first floor is laid directly on the ground. 

The footings at the south end of the building were designed for full panel 
loads in order to take care of the future loads that will come on these columns 
when the building is extended. The weight of the present south wall is now 
carried upon these footings, but when the building is extended this weight will 
be replaced by the weight of the floor construction extending to the next row of 
new columns. Between the footings at the south end of the building is a 
concrete curtain wall 13 in. wide and extending 4^ ft. below the first-floor level. 
This carries the weight of the 13-in. brick wall of the first story. The interior 
column foundations are stepped footings reinforced by two layers of steel bars 
placed near the bottom. The size of the bases varies from 13 ft. 6 in. to 
17 ft. 9 in. square. 

77 



REINFORCED CONCRETE BUILDING, CHICAGO. 



[«5NC£ErE] 



The floors are of the Akme system of flat slab or beamless construetion, 
and are 11 in. thick. They are designed for a live-load of 150 lb. per sq. ft., 
with panels 28 by 25 ft. At the south end, the floor slabs extend 4 ft. beyond 
the centre line of the columns. The temporary south wall is carried on canti- 
lever extensions of the floors, which are extended to this distance to provide 
for carrying the next panel of floor slabs when the building- is lengthened. A 
pair of steel angles forming a Z-section is secured to the face of each floor slab 

.„» r> ^. by anchor bolts 

S* r 







#>. ■•:!'• I ■:•■/•• 

.Vi'/Xi'.-' r "VJV.f. * sc 



l?t_Floor_ *£_ . 



<—0'- -> 

Section A-A 






\c-fW- -A 
Section B - B 



4 A ! 16, 1 * M> 21 'Bars, in top bet.icols. 
I I 16, r 6 xll' » in bott. of cols. 

'■ , fifflft " *'' 

*? 1 I -^-v--K.-J ! I L..^»^-%- | -J : J 

Eleva+ion 



thus forming a shelf 
to support the end 
of the future slab, 
as shown in Fig. 2. 
The angles are at 
present incased in 
concrete which has 
been cast separate 
from the general 
floor slab so that 
when the extension 
is made this concrete 
can be easily 
removed, leaving the 
steel shelf angle pro- 
jecting. 

A mezzanine 
floor covers a por- 
tion of one panel 

between the first and second floors. This is supported on two columns and 

suspended by lour sets of hangers. Each hanger consists of two or three i-in. 

round rods 11 ft. 8 in. long, with top and bottom bearing plates made of 5-in. 

channels. These plates are embedded in the concrete of the mezzanine floor 

and the floor above. 

The columns are //^J^'tK S"tff f ""I" 5 "* fLAJf .Il'S tob 

<? x6> Stub Bar. * Mfc5!^!fi&!g!* £ I B&S&*PS 



all of octagonal sec- 
tion, varying from 
40 in. to 24 in. out- 
si d e diameter. The 



i : ^. si 



V/A'l 



^T 



S 



* "*""" ""^•■^■•^v..-:y^ ;: vv ^v v -. v ^ VAV::::::r- . vw? l^ > ... ~4o-??-ll 



Plan 
Fif4. 1. Continuous Footing. 
Reinforced Concrete Building for the Ford Motor Co., Chicago- 





column capitals an- Section a+ 

, , ... South End 

also octagonal, with 



Detail of Cantilever 
at "A" 



Section oct 
Alley Side 



Section at 
Wabash Ave. 
Side 

a Hare of 45 deg. mm p .^ ^ Col(linn ,, eads and F i oor S i a b s with Detail of Cantilever Extension at 

the vertical and a top South End. 

.. ,. , . Reinforced Concrete Building for the Ford Motor Co.. Chicago. 
diameter of 5 it. in. 

Above the flaring head is a column plate 7 ft. square by 9 in. thick, the lower 

edge of this plate being bevelled. The columns are spaced 28 ft. C. to c. 

longitudinally and 25 ft. laterally, except that in the central hay of the building, 

where th< railway track is supported, the columns are spaced 35 ft. c. to c, 
laterally. 



7 ; 



rs, CONMTMJCI ionaT) 

j' Vt.NC.lNH K'IM. — J 



REINFORCED CONCRETE BUILDING, CHICAGO, 



There are no spandrel girders required in tins floor construction, l>ui in 

some instant es i !><■ concrete 



2<l d Floor Linn 



— i ■ — S!" •'• — r 



* 



-n 



\ 



I v 



-/J-- 



>:< 



Main Co! 






/•' 



/.* 



j » • * y-y/i 



>m 



W. i ..\.-i .j:.i--i..i..t. •.<■■»■•- ■- .:.,. 






Cros^s- Seo+ion — 






« . -i 



A«— ~-fcj-A 



Plan of 

Columns 



<Col. 



B3SE3 




^^{"^rr^WFp 



23 



!-A-l-Ji-.».r--fc-.-.-.->J 



Seo+ion 
A-A 



Eleva+ion of Col. 
and Girder ort B 



section has been dropped down 
.1 few inches below ihe ceiling 
along the wall to carr) the 
terra-cotta trim for the 
terior. The east, or alley wall 
ol the building is made ol < on- 
crete instead of brick, and on 
this side ili<- concrete columns, 
floors and spandrel w^lls were 
casl integrally. 

Concrete Track Girders.— 
The only girders in the building 
arc those carrying the railway 
track, the crane runways and 
the monitor roof. The railway 
lines adjacent to the building 
are elevated, and a switch 
track runs through the building 
at such an elevation as to bring 
the car floors level with the 
second floor of the building. 

This track is in the central 35-ft. bay of the building, and is carried in a concrete 

trough 16 ft. wide and about 5 ft. deep. The main track girders are 7 ft. 3 in. 

deep and 16 in. thick. Between these girders is a bottom slab 21 in. thick, 

carrying the track. One of the main girders is carried on the main columns, 

while the parallel girder is carried on independent columns spaced 28 ft. c. to c. 

T h e second 

floor projects 

a short dis- 
tance beyond 

one of the 

main track 

girders, thus 

providing a 

protected 

space under 

the overhang- 



Fig. 3. Reinforced Concrete Bridge Carrying Track. 

Reinforced Concrete Building for the Ford Motor Co. 

Chicago. 



T 

i 









N 




ing floor for 
wires and 
heating pipes. 

The track 
is laid with 
wood ties and 
stone ballast. 
The w hole 
bridge struc- 

c 



? 'Top Line of Crane ■ 






Carriage 



Co!. 



If 

h ; ^ 



■35 




Half Eleva+ion 
of Tru&j 



Half £.leva-Hon a+ 
lrrrermedia+e Beam 



Fig. 4. Reinforced Concrete Trusses Carrying Monitor Rcof. 
Reinforced ConcRETE Building for the Ford Motor Co., Chicago. 



REINFORCED CONCRETE BUILDING, CHICAGO. [ QQNCRE11J 




80 



[7, IONMI.MH I ION \l 
Ifi 1 NCilNl 1 l-'IMt — 



REINFORCED CONCRE ll BUILDING, CIIIC.\<,<> 



i lit t design is in accordance wuh the recommended practice ol the American 
Railway Engineering Association. The construction is shown in Fig. \, and 
Fig. s is a view ol the firsl floor, showing al the Icfl one oi the heavj ti ick 
girders supported on the main columns. 

Concrete Balcony Floors and Roof Trusses, l' 1 i' 1 * central panel, 35 ft. 
wide, there is an open space from the second floor to the roof, except al the 
extreme north end where there is a floor panel 28 1>\ 35 It. <-it each floor. This 
open well or craneway is provided with an overhead bridge crane which runs the 
entire length ol the building and serves all floors 1>\ means ol cantilever 
balconies extending 8 ft. 6 in. from the column centres. These balconies are 
extensions of the ll >oi slabs, and are of varying lengths; 1 .j ft. on ilx - '>th floor, 
38 ft. on the 5th floor, 42 It. on the 4th floor, and 56 ft. on the 3rd floor. So 
there is always an open space 14 ft. long by 6 It. H in. wide on each balcony 
from which to receive and deliver materials or automobiles from the bridge 
ci inc. 

One of these 8^-ft. cantilever slabs 42 ft. long was tested with a uniform 
test load of 310 lb. per sq. ft., equal to 2,hoo lb. per lin. It., in addition to 
weight of construction. Under this load the deflection was .^ in. at the outer 
edge, after the load had been on for 24 hours. 

Below the roof level the two central rows of columns carry the reinforced 
concrete longitudinal girders for the runway tracks of the bridge crane. Above 
these runway girders rise the side walls of the monitor roof. 'Idle roof is carried 
by reinforced-concrete trusses, having a span of 36 ft. and spaced 28 ft. apart. 
As shown in Fig. 4, these trusses are of the king-post type with a rise of 
8 ft. 6 in. 'I"he bottom chords of the trusses are simply tie rods incased in 
concrete, but the section was made sufficiently strong- to act as a beam to carry 
its own weight. The bottom chord and post are rectangular, while the uppei 
chords are of T-section, 18 in. deep and 36 in. wide over the flanges. 

The trusses are supported at the ends by the walls of the monitor roof, and 
are connected at the ridge by longitudinal T-girders 36 in. deep. The roof 
between each pair of trusses is supported by two intermediate rafters of 
T-section, dividing the area into three panels 7 ft. 4 in. by 16 ft. long on each 
side. Each of these panels is covered by a copper and glass skylight. At the 
north end of the building an arched concrete wall or girder replaces the concrete 
truss. This is 9 ft. deep at its ends and 14 ft. deep at the centre, and is faced 
on the exterior with brick and terra-cotta. 

Fig. 6 shows several of these special features of the building, being an 
interior view of the central craneway. Freight cars will be noticed standing on 
the depressed track, with car floors level with the second floor of the building. 
It will be seen that there is a wide unloading space on one side of the car and 
that the cantilever balconies on the opposite side overhang the cars slightly. 
This craneway or court will be inclosed entirely with steel sash and wire glass, 
with sliding doors opening from each floor on to the balconies. 

Construction Plant. — During the construction of the building the concrete 
materials were brought in by cars on an elevated trestle and unloaded into 
storage bins south of the building site and beneath the track. From these bins 
the sand and gravel was delivered by means of a belt convevor to elevated bins 



c 2 



81 



REINFORCED CONCRETE BUILDING, CHICAGO. 



[CQNCBETFJ 



above the measuring- boxes, which in turn were above the concrete mixer so 
that measured quantities of gravel and sand were discharged into the mixer, 




Fig. (, View Showing Interior of Building with Cantilever Balcony Floors and Concrete Roof Trusses 
Reinforced Concrete Building for the Ford Motor Co., Chicago. 

together with the proper amount of cemenl and measured quantity of water for 
each batch. The i-yd. mixer discharged the concrete into a 2-yd. hopper 
feedmg a i-yd. bucket in the elevator tower. The mixing plant and tower were 
Hz 



j,tX>NMVlR-riONAlA 
fVFJM(.lNKl WIN(. —J 



REINFORCED CONCRETE HOLDING, Clin i< 



located at the south end of the building. All of the concrete was spouted 
directly to the floor Forms, except thai the concrete for the monitor root was 
placed bj means ol carts. 







Fig. 7. View Showing Concrete Plant. 
Reinforced Conxrete Building for the Ford Motor Co., Chicago, 

The spouting equipment presented some features of special interest which 
are shown in Fig. 7. In the first place, the chutes were rigid and self-support- 
ing, so that there was no sagging in them. The chute consisted of a pair of 
8-in. channels placed back to back, 12 in. apart, with bottom lacing and an 

83 



REINFORCED COXCRETE BUILDING, CHICAGO. [CONCRETE] 



interior trough of sheet steel. This formed a chord member that was trussed 
from beneath by struts and cables. The main chute extended from the receiving- 
hopper a; the top of the elevator tower to a shorter tower near the centre of 
the building-; from this second tower extended a second chute pivoted at the 
tower and supported by a latticed steel boom. The lower end of the boom 
was carried on a circular track around the tower, thus permitting' the boom and 
chute to swing through a complete circle, reaching- all parts of the floor. 

An unusual feature was the use of flexible drop pipes, by which the concrete 
could be taken from several openings in the revolving- chute and delivered to 
the forms. These vertical pipes were of metal, spaced 10 ft. apart and fitted 
with g-ates at the upper end which might be opened to draw off concrete from 
the chute. 

The architect for the building- was John Graham, of Detroit, supervising- 
architect for the Ford Motor Co., and the structural desig-n was made by the 
Condron Co., eng-ineers, of Chicag-o. The general contractor was E. L. 
Schneidenhelm, of Chicago. 




Fip. 8. Exterior View. 
Reinforced Concrete Building for the Ford Motor Co.. Chicago. 



fi T CONCTUI 'CTIONAJJ 

' Al NC.1NI 1K1NC. — I 



WHAT IS A I : J i I CONCRE1 B 










to ' 




WHAT IS A 
1:2:4 CONCRETE? 



By H. C. JOHNSON, Lecturer, University College, Cork. 

The following article ivill probably interest all those ivho make a special study of the 
all-important questions of Concrete aggregates and the mixing of concrete. ED. 



1\ these days of scientific pro-portioning of materials for concrete more ink upon the 
subject seems absurd, but when it ran Be definitely stated thai there is as much 
difference in the amounts of cement in the "popular" 1:2:4 concretes as there is 
between 100 bags of cement and 130 bags of cement it may be admitted that we have 
new ink upon the subject. 

In order to have some basis upon which to consider this astonishing difference it 
will be necessary to state the general requirements of the great majority of 1 : 2 : 4 
concrete specifications : The concrete shall be composed of water, with one volume 
of cement, two volumes of fine aggregate (sand), ami four volumes of large aggregate. 
The cement must pass the requirements of the British Standard Specification , while 
the others must be of good quality and clean. 

Now that specification does not look as if it would allow a contractor to save ot- 
iose 30 bags of cement— the difference between ioo bags and 130 bags- and still allow 
him to fulfil its demands, but it is so. 

If that 24 per cent, can be saved by a contractor, it goes straight into his pocket, 
plus the saving in not having to handle that quantity; in other words, it is a clear 
profit, but a loss to the structure — a loss that seriously reduces its strength. This does 
not imply wickedness on the part of the contractor, but rather carelessness on the part 
of the architect or engineer. 

The trouble is that the proportions 1:2:4, with too many people, stand for 2,000 lb. 
per sq. in. at 28 days. Some mixtures of 1:2:4 W *H allow that strength at that age — 
most will not come nearer than 1,500 lb. Such a statement does not condemn concrete 
— it condemns the makers. 

For the present we will leave out the question of strength and consider onlv the 
amount, or, better still, the volume percentage, of cement in various 1:2:4 concretes. 
After all, the cement is the only thing that "cements," and the more of it, all other 
things being equal, the stronger the concrete, statements to the contrary notwith- 
standing. 

Before going further the writer will assume that the reader will admit the truth 
of the following facts : — 

(a) Sand, stone and gravel are inert materials with absolutely no cementing 
power, and are only used to dilute neat cement, because neat cement would be too 
expensive to use alone. [This is quite apart from the question of using neat cement 
alone, since no one would use neat cement so.] 

(&) Aggregates possess voids, or air spaces, ranging from 25 per cent, to 50 per 
cent, of the gross volume they occupy. 



H. c. johnson. [CONCRETE] 



(i) It is incorrect to speak of a 1:2:4 m * x as a ! '• 6 mix, since it may convey 

the impression that 6 parts of sandy gravel with 1 of cement is the same as 4 parts 

-tone and 2 parts sand with 1 of cement. 

(J) It is generally considered that a 1:2:4 mix gives a linal volume of slightly 

over 4 parts, so that one-quarter of the mass is cement. 

The following case illustrates the trouble caused by a loose specification. The 
architect called for " concrete to be composed of 6 parts of stone and sand, both 
measured by loose volume, to 1 part of Portland cement . . . by volume." The con- 
tractor was fortunate enough to find on the site a gravel of good quality, and asked 
the architect's permission to use it, which was readily granted. The contractor pro- 
ceeded to mix 6 parts of the gravel with 1 of cement, when the architect stopped him, 
pointing out that the gravel should first be screened to remove the sand and then 
remixed in the proportions of 2 parts sand to 4 parts gravel. The contractor claimed 
he had a right to use 6 parts to 1 of cement. Neither side would give in, and the case 
went up for arbitration, when both admitted faults — the architect that his specification 
should have read 1 volume cement, 2 volumes sand, and 4 volumes stone; the contractor 
that he thought, when he was allowed to use the gravel, that 6 parts to 1 of cement 
was equal to 4 stone, 2 sand, and 1 cement. 

The actual percentage of cement in various 1:2:4 concretes. 

No. 1. — We will suppose that the above contractor had his way, and proceed to 
find the actual percentage of cement in his concrete. 

The percentage of voids in the usual run of bank gravel will be about 33. Six 
parts of this mixed with 1 part of cement by loose volume will produce 6 parts of 
finished concrete. But since cement (of average fineness) loosely measured reduces to 
about 70 per cent, of the original volume upon wetting there will be only -^ of 1 part 
of cement to 6 finished volumes of concrete. Ratio 1 to 8'6=ir6 per cent, cement; 
weight per cu. ft. = 118 lb. [Also note that of the 2 parts (33 per cent.) void, only a 
trifle over one-third is filled.] 

No. 2. — If the gravel is passed over the sand (i-in.) screen and also the f-in. 
sen en, a large aggregate with about 38 per cent, voids and a small aggregate (sand) 
with 40 per cent, voids will be obtained. These mixed 4 parts large aggregate, 2 parts 
small aggregate, 1 part cement, will produce about 5-6 parts of finished concrete. Ratio 
1 to 8=12*5 P er cent, cement; weight per cu. ft. = 140 lb. 

No. 3. — If only material that passes the |-in. screen and is retained on the f-in. 
screen, and which will contain about 42-^ per cent, voids, be used as large aggregate 
and a mixture of 4 parts large aggregate, 2 parts small .aggregate (as before), 1 part 
cement, there will be produced 5^ parts finished concrete. Ratio 1 to 7-5 = 13*3 per 
cent.; weigh! per cu. ft. = 143 lb. 

No. 4.- A crushed limestone passing the |4n. screen and retained on the |-in. 
screen will contain 45^ per cent, voids, and if mixed 4 parts large aggregate, 2 parts 
smaH aggregate (sand from gravel), 1 part cement, there will be produced 4'<)2 parts 
finished eonereie. Ratio 1 lo 7-14-25 per cent.; weight per cu. ft. =.-■ 143 lb. 

No. 5. — A crushed limestone passing the .\-in. screen and retained on the |-in. screen 
will contain 48$ per cent, voids, and if mixed as No. 4 will give nearly the same finished 
volume. Ratio 1 to 7=14*25 percent.; weight per cu. ft. = 144 lb. 

Now some engineers prefer a sand with the liner particles removed and a larger 
large aggregate; we will therefore make two more mixes, using such material. 

No. (>. — A crushed limestone passing |-in. screen and retained on the .\-"m. screen 

will have about 48 per tent, voids (about same as No. 5 stone), and if mixed 4 parts 
large aggregate, 2 parts small aggregate (sand taken from the gravel and passing i-in. 
screen, retained on ,',,-in. screen -14 per cent, voids), i part cement, there will be 
S6 



« v LNCilNKKWlMi — 



WHAT IS A I : 2 I CONCRE7 / 



produced 4*8 parts finished concrete. Ratio i to 6*85 14*6 pei cent.; weight pei 

cu. li . 149 It). 

\,>. 7. A gravel sized as fen las! mix (No. 6) will contain 13 pei cent, voids, and 
if mixed 4 parts large aggregate, 2 parts small aggregate (as foi No. 6), 1 pari cement, 
there will be produced .s' m parts finished concrete. Ratio 1 to 7*3 13*7 per cent.; 
w eight per cu. li . [44 lb. 

Other engineers and architects prefer to make a mortal oi the sand and cement 
in the ratio of 2 parts sand to 1 part cement, then use 2 parts <>l this mortar t<> 4 parts 
stone. With this method we will make two more concretes one stone and one graw I. 

\<>. 8. Using the gravel passing the J-in. screen and retained on the \-\v\. screen, 
but with material from \ In. to \ in. removed, voids will equal 35$ per cent. Bj mixing 
2 parts sand (obtained from gravel) passing |-in. sieve, retained on rV-in. sieve, con- 
taining 40 per cent, voids, with 1 part cement, and then wetting these to make mortar, 
2*64 parts mortar will be produced (a finer sand will produce more). These mixed, 
4 parts large aggregate, 2 parts mortar, will produce 4*<)o parts finished concrete. In 
order to obtain the ratio it must be remembered that 1 part cement is contained in the 
2*64 parts mortar; therefore by using only 2 of the 2*64 parts of mortar only 76 per cent. 

"1 X "7 f\ 

of the cement is in the concrete. Ratio = =1 to q-ic = io*7 P er cent.; weight 

per cu. ft. — 142 lb. 

No. 9. — Using crushed limestone of same sizes as above, which will have 45 per 
cent, voids, and also mortar of same proportions: if mixed 4 parts large aggregate, 
2 parts mortar, there will be produced 4*4 parts of finished concrete. Ratio (worked 
.as above) =1 to 8*3=12 per cent. ; weight per cu. ft. = 145 11). 

Returning now to true 1:2:4 concretes (the last two are not): 

No. 10. — Using crushed stone passing |-in. screen and retained on i-in. screen, 
and which will have 4(1 per cent, voids, and a very good quality but very fine sand 
passing ^V m - sieve and retained on 7 ' (T -in. sieve, and making a concrete with these — 
4 parts large aggregate, 2 parts small aggregate, 1 part cement — there will be produced 
4*33 parts finished concrete. Ratio 1 to 6 , 2 = i(vi per cent. ; weight per cu. ft.= 144 lb. 

The following four mixes clearly show that a fine sand produces more, but a weaker, 
concrete than coarse sand : — ■ 

.Vo. 11. — A f-in. to |-in. washed gravel, with a sand §-in. to ^-in., but in which 
the coarse particles predominate (same sand as used in Nos. 1 to 9 inclusive, but care- 
fully washed) — 4 parts large aggregate, 2 parts small aggregate, 1 part cement — 
produces 5*26 parts finished concrete. Ratio 1 to 75 1 = 13*3 per cent.; weight per 
cu. ft. = 144 lb. 

No. 12. — Washed gravel as above, sand scunc sieves as above, but one in which 
the fine particles predominate — 4 parts large aggregate, 2 parts small aggregate, 1 part 
cement — produces 5*38 parts finished concrete. Ratio 1 to 7*7 = 12*96 per cent. ; weight 
per cu. ft. = 146^ lb. 

No. 13. — A washed crushed limestone, same size as No. 11 and same sand — 4 parts 
large aggregate, 2 parts small aggregate, 1 part cement — produces 4*83 parts finished 
concrete. Ratio 1 to 6*9=14*48 per cent.; weight per cu. ft. = 148^ lb. 

-Vo. 14. — Washed limestone same as for No. 13, and sand same as used in No. 12 — 
4 parts large aggregate, 2 parts small aggregate, 1 part cement — produces 5*0 parts 
finished concrete. Ratio 1 to 7*14=14 per cent.; weight per cu. ft. = 149^ lb. 

To this list might be added six other mixtures just as carefully made by the writer 
as those above, but since we have, in the ones given, the maximum and minimum 
percentages of cement found to be in the twenty 1:2:4 mixes made, no useful 
purpose, under the present title, would be served by including them, since they either 
give the same percentages, or nearly the same, as those listed. 

87 



H. C. JOHNSON. 



ilDNCBETEI 













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[ j.l'ONMk'IIC I ION \ I 
[<•> 1 NG1NEER1NO — , 



WHA T is A 1:2:4 CONCRETE 



Figures like the above are generall) mine easil) remembered ij in the form 
table, and that given contains all the necessar) information foi tin furthei considers 
of the man) interesting points these tests show. 

Ii is \<i\ necessar) to impress the reader with the facl thai all measurem 
were made b\ loose volume in the proportion ^ large aggregate, 2 small aj 
to 1 cement jusl as would be made on the j<>l>, the methods on which tin writei 
fullv acquainted with. The reason foi taking the 1/ibertj ol stating the last-m nti< 
facl is thai man} are inclined to take lafeoraton work and laborator) suggestions with 
a grain of salt, or with an eas) mind, so to speak. From where else, pray, do the) 

obtain their safe value of [6,000 lb. per sq. in. for steel, or safe for columns km 

k 

from the laborator) ? To our laboratories, therefore, we must look for the super- 
concrete, and it is hoped that the present article may do its little towards thai end. 

In order to obtain uniformity in proportions, the weights per cubic tool of the 
sands and the cemenl (the same brand Ship Canal Co.'s being used for all mixes) 
were obtained at the start and used for mixing. All materials dry. 

In summing up the points contained in the table no use will be made of \os. 1 to 
S and () because they arc not 1:2:4 concretes in the strict sense, although mam 
have been guilty of so considering them guilt) because even departures from rule-of- 
thumb methods, which are often satisfactory, must not be made to satisfy theory 
without first proving theory to be correct practically. The table Illustrates the 
following facts : — 

(a) 1:2:4 concrete No. 10 contains 29 per cent, more cement than 1:2:4 
concrete No. 2. 

(b) Stone concretes on the average contain 10 per cent, more cement than gravel 
concretes. It is therefore not fair to expect gravel concretes to be as strong as stone 
concretes. (" American Civil Engineer's Pocketbook " notes that gravel concretes at 
one year are o per cent, weaker than stone concretes.) 

(c) The percentage of voids in gravel being smaller than in stone, less sand should 
be used : ih parts sand (on the average) to 4 parts gravel will produce a concrete worked 
as easily as, if not more easily than, 2 sand to 4 stone. 

(d) Gravels passed through and retained on screens as used for stone always have- 
less voids; the popular idea is that they would be the same. It can be admitted that 
if stone could be " hand placed " into a receptacle, a very small percentage of voids 
would result. This indicates that stone concretes, unless they had considerable sand 
(2 to 4), would not be so reliable as gravel in the matter of density. 

(e) Gravel concretes mixed 1 : 2 : 4 are 3 lb. per cu. ft. lighter than stone concretes. 
Proper proportioning will easily make up this 3 lb., in spite of the fact that the specific 
gravity of gravel is only 2*51, as against 2*70 for stone. 

The writer has used the terms large aggregate and small aggregate on purpose to 
draw attention to the fact that sand is only finer gravel or granite or quartz, is an inert 
material just the same as the larger materials, and has to be " cemented " by the 
cement just as the larger particles. It is no use talking of mortar filling the voids or 
anything of that sort. Mortar is used by bricklayers and masons to btd two plane 
surfaces together; concretors use inert aggregate and cement with which to bind it 
together; but the outstanding fact is that the smaller the aggregate (all other things 
being equal) the weaker the concrete. There is no need to quote authorities; they are 
many, and have established the fact. In view of this last, the less fine aggregate (sand), 
providing a thoroughly workable concrete is produced, the better. 

This article contains no strengths of these mixes of 1 : 2 : 4 concretes, and this is 
not necessary under the title, but it was stated at the beginning that " the more cement 

89 



h. c. johxson. [OiPCBETEl 

the stronger the concrete " statements to the contrary notwithstanding/ 1 Statements 
have been made, and tests devised to prove, that — 

(a) Reducing the percentage of voids to the absolute minimum possible, and filling 
these with cement, products the strongest concrete. 

(b) Any cement beyond that necessary to fill these voids is waste and dees not 
increase the strength. 

((•) Just as a carpenter uses the minimum of glue in making' a joint, so one should 
use a minimum of cement in making concrete. 

Regarding (a), it is possible to reduce the percentage of voids to 10 by using a 
graded sand, but 10 per cent, of cement has to coat the surface of the remaining 90 per 
cent. Could this be the strongest possible concrete? 

Regarding (a) and (b), a recent paper sought to prove that a mix of 1:2:4 was 
not stronger than one of 1 : 3 : 7. It was not at one month, but it was over 50 per 
cent, stronger at three months, and at a year would probably leave a greater gap. In 
the one-month test the 1:2:4 concrete contained more of, what was then, the weak 
material than did the 1 : 3 : 7, but at three months it began to assert its value, with 
the result stated. 

Regarding (c), there is no sense in this argument, siince the carpenter, like the 
mason, is only sticking together two plane surfaces (in a tenon, several), and would 
therefore not obtain greater strength any more than an engine could pull more by using 
a longer coupling-chain. 

Such statements would suggest that neat cement in compression would not be so 
strong as a mixture of very strong stone and cement. Two tests made by the writer 
can be put forward as against this idea. A first-class neat cement cube gave 12,064 lb. 
per sq. in. at three months. Another cube made of hard whinstone (probable crushing 
strength 20,000 lb. per sq. in.) 2\ parts, and the same cement as above to fill the voids, 
one part, stood only 7,300 lb. per sq. in. at eighteen months. 

It may be admitted, therefore, all other things being equal, the more cement the 
stronger the concrete. Gravel concrete has suffered for years, because for apparently 
equal quantities of cement it is not .as strong as stone concrete. 

The whole trouble lies in the fact that the amount of cement is not based 
on the finished volume of concrete. 

Now, in suggesting remedies or corrections, other investigators go too minutely 
into proportions, and therefore do not succeed in carrying the " practical " man with 
them in their ideas; but the following method, not entirely new (Mr. YV. B. Fuller years 
ago suggested a similar method, but gave no figures that the writer can find), ds simple, 
and after once done can easily be remembered. 

To Determine Correct Proportions. 

Correct method of proportioning 1:2:4 concretes. Apparatus required: 2 pails 
holding \ CU. ft. each, trowel, scales to weigh to 100 lb., materials to be used for the 
concrete, and water. Before mixing, first determine the percentage of cement to he 
used. For instance, using the figures given in the table, and considering that two 
engineers out of three prefer stone concrete, we will find an average for all the 1:2:4 
mixes, thus : — 

Average percentage cement in stone concretes ... ... = 14*32 

„ ,, ,. gravel „ =13*15 

If 2 engineers prefer stone ... ... ... 2X14*32 = 28*64 

and 1 engineer prefers gravel ... ... ... 1 X 13*15 = 13*15 

I 

3 41*79 

1 

Average = 13*93 per cant, 
or, say, 14 per cent, compaol cement = 2o per cent, loose volume. 
90 



^knoinkkwInT^I WHAT IS A 1:2 : 1 CONCRET1 



Take one pail .md measure '40 cu. ft. lai i \U and turn this on to 

board, then measure ' 10 cu. ft, a m< nl carefully. II I : * . 1 1 « is grav< I, 1 ( 

out "125 cu. ft. sand (it stone, '15 cu. ft.) and turn these on to mixing board and 
wiih water till into othei pail, noting volume and weight. This will not usualh 
produce J cu. ft. 01 .1 pailful (which is necessan to obtain the correct percenl 
ih. .inn mm of cement used), so continue adding sand in small lots carefull) measured 
until a working consistency is obtained, after which weigh and note volunn ; il pail is 
not full, add large aggregate, noting the volume, until |>;ii! is full. The last figures 
obtained give 1 1 1 < - proportions for the mix. 

Ex win i-. 





\\ 


r eig 


hi. 


Weight 


Volume. 




lb. 




per cu. f 1 


'435 




62 




M4 


•460 




67 




i45i 


•488 




7' 




MS* 



Gravel *4 cu. ft. + *i cement + '125 sand ... 

'4 »i +'' 11 +''5 

•4 ., +'i ., +''75 11 ••• 
( This produces a workable concrete, therefore add more stone. ) 

•425 ,, 4-- 1 ,, +-175 "5° 2 73^ M 6 i 

N.B.- -No account need be taken of the water used, but a trifle more than sufficient 
should be used in first batch and none added after. 

The correct mix, then, is '425 large aggregate = 4^, "175 small aggregates if, 'ioo 
cement=i. Of course, these figures will only apply to the concrete using this sand. 

Another sand, with the same gravel, might produce the proportions 1 : r<> : 4, but 
there is still the same expenditure of cement for the same finished volume of concrete. 
Smaller proportions do not indicate smaller finished volunn s. 

Using this method, the two following concretes were produced, using the 14 per 
cent, wetted cement = 20 per cent, by loose volume: — 

A. — Gravel 4^ parts, fine sand 1^ parts, cement 1 part. Weight per cu. ft., 148 lb. 

B. — Same gravel 4 parts, coarse sand i*6 parts, cement 1 part. Weight per 
cu. ft., 146 lb. 

Two others, using stone and the above sands, called for proportions so near 1:2:4 
(one was No. 14 in table) that nothing would be gained by altering those proportions. 
This would not prove that stone concretes need not be proportioned, since only one siz<- 
stone was used in these two mixes. 

Correct specification for concrete equal to average 1:2:4 concrete — i.e., con- 
taining 20 per cent, by loose volume of dry cement equal to 14 per cent, wetted : 

The concrete shall be composed of perfectly clean crushed stone or gravel passing 
the -in. sieve and retained on the -in. sieve (|-in. suggested); the particles of gravel 
shall have a least dimension of not less than one-half the greatest dimension, the stone 
a least dimension not less than one-third the greatest dimension, and no flakes that 
can be levered with a knife from the surface of any of the particles. Specific gravity 
not less than 2*5. 

The sand shall be thoroughly washed, and when dry shall pass the §-in. sieve and 
be retained on the 75-in. sieve, the particles shall be as nearly spherical as those of the 
gravel mentioned above. Specific gravity not less than 2 - 5- 

The cement shall easily pass the minimum requirements of the British Standard 
Specifications of August, 1910, when not less than 22 per cent, of water is used for 
neat cement specimens and not less than 8i per cent, for mortar specimens. 

The proportions for mixing shall be determined on the principle' that the minimum 
amount of sand consistent with easy working of the mass shall be' introduced (not 
more than will give a ratio of 1 sand to 2 stone for stone concrete, or not more than 

9 1 



h. c. johnson. [Concrete] 

will give a ratio of i sand to 2*4 for gravel concretes), and that the resultant 

thoroughly mixed concrete shall not contain less than 20 per cent, of cement by loose 
volume or 14 per cent, by wetted (22 per cent, water) volume. The weight per cu. ft. 

when wet shall not be less than 145 lb. 

Samples of the materials proposed to be used shall be deposited with the under- 
signed (architect or engineer) before amy concrete materials arrive on the job, and the 
proportions to be used shall be proved to be as called for, by a demonstration in the 
presence of the undersigned, who will then give written authority to use such propor- 
tions if found correct. 

The latter part of this specification is strictly in keeping with the sense of this 
article. The first part is not, but is nevertheless true and necessary to a complete 
specification, and is therefore included. 

The specimens made for this article will be tested in due course, and the results 
given, when the effect of a rational method of proportioning will show itself. 

The writer, in conclusion, .appeals to other investigators to give, in future, the 
percentage of cement per finished volume of any concretes they may report upon, as 
bein^ the best way to compare strengths for given expenditures in cement. 



9 2 



J. CONMI.MKTIONAl? 
'^ 1 N(,IN1 l |>|M, ^ 



LIGHTNING ON A ST1 EL DOME, I 



T^5^7 







AN INSTANCE OF 
LIGHTNING ON A STEEL 
DOME AND REINFORCED 

CONCRETE WALLS. 



The following particulars regarding tin- effect of lightning 

on reinforced concrete are the result of son;, at ions 

m.iJe by Mr, C. D. Perrine of the Argentine National Observatory at Cordoba* He first 
reported on them in J letter published in "Science," and afterwards reprinted in the 
* ' Engineering News. ' '— ED. 



It is evident, says the Engineering News, that the domes and reinforcing were 
carefully grounded to lead lightning discharges safely to ground. Freedom 

from disturbances within the domes was expected, as the construction was 
most favourable for such protection. Mr. Perrine's report reads as follows : — 

The centre of the storm, judging from the clouds and their motions, was 
not over a mile south by south-east of the observatory. In nearly all the storms 
which I had seen here previously the discharges were nearly all between 
clouds. (Perhaps because most of them occur at night?) In this storm nearly 
all of the discharges were between the clouds and earth. 

The direction of motion of this storm, as is usually the case, was from 
south to north. After some half dozen discharg-es close to the south there 
was a heavy one to the north-west about three hundred metres away — then 
another to the north-east about the same distance. 

On account of this beirg a heavy storm and apparentlv passing directly 
over us, I was interested to see what the effect would be on our two new 
reinforced concrete walls and steel domes sheathed with galvanised iron, and 
was outside among' the central group of buildings and not over 100 ft. from 
the domes in question, one of them in full sight. 

A minute or two after the flash to the north-east, mentioned above, there 
was a general illumination close by, followed almost instantly by the ripping- 
sound of "a very close stroke. The interval between the flash and the sound 
was certainly not over one-tenth of a second. To me the sound appeared to 
be made up of three or four separate discharg-es blended into one — not con- 
secutive. 

The power and light currents were cut off until about 6 p.m., when it was 
found that fuses had been blown on our lines (which were special ones) just 
outside the step-down-station, some 400 metres away. Xo other effects of the 
storm were noticed in or near this station. 

The dome, which had just been completed, was barely out of sight from 
where I stood, and no one at the observatory seems to have seen the actual 
flash. A peon, however, in the grounds of the Meteorological office, about 
100 metres away, had a full view of both domes and buildings, was facing' them 
and saw the flash just over and about the new dome. This accords well with 
the direction and distance from my point of observation. 

95 



LIGHTNING ON A STEEL DOME, ETC. [CONCRETE 



After hearing of this observation I made a careful examination of the dome, 
and in particular the connection of the copper eable with the track upon which 
the dome revolves, which forms the connection between the metal dome and 
one of the vertical I-beams embedded in the concrete for grounding the circuit. 
The lightning-rod proper extends about a metre above the highest part of the 
dome and terminates in a brush of heavy wire. Xo signs whatever of any 
discharge have been found at any point about the dome. 

Close to the dome stands the wooden derrick which was used in its con- 
struction, the top of which is about 2 ft. higher above the ground than the 
lightning-rod. Three wire-cable guys lead off to trees; two of them actually 
touch the ground — but scarcely so — and a fourth goes to a brick build'ng. 
The cable used for lifting did not touch the ground. Careful examination of 
all of these points failed also to disclose the slightest sign of a spark. 

The three wires of the alternating power circuit pass close to both dome 
and derrick. 

The bolt which struck the dome was undoubtedly not a light one, for it 
frightened badly a number of persons in the residences near by, and was 
described by several as a very bright flash. I do not think, however, that it 
was an especially heavy one, possibly not so heavy as most of the others which 
struck in the vicinity. 

The peon who saw it from the neighbouring quinta was seated at the time 
under a shed and watching the dome. He says the flash appeared to descend 
as a single ray, striking the lightning rod and then the whole surface of the 
metallic dome appeared to be covered with sparks or flashes. 

It seems certain, therefore, that the dome was actually the principal point 
of discharge for a fairly heavy flash of lightning. (It is uncertain how much 
of the discharge was taken by the derrick, but it would appear to have been 
relatively small.) Also the induced currents in the light and power lines were 
sufficiently heavy to blow the fuses in both. 

At the time the bolt struck, there w r as a peon inside the closed dome, clean- 
ing the running-gear. When questioned he said he had felt nothing nor had 
he noticed anything unusual beyond the heavy noise. 

This experience seems to be a fairly severe test for such a construction — 
a metallic dome surmounting concrete walls which are heavily reinforced with 
iron — the metal in the walls having" a good ground connection and being 
connected also with the dome. 



94 



[9-OON5IWITIOIAP 
IA.KNniNK I-,KING-~ 1 



CONCRETE IS MODERN SANITATION, 




RECENT VIEWS ON 
CONCRETE & REIN^ 
FORCED CONCRETE. 



Recent Papers & Discussions. 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method ive are adopting, of dividing the subjects into sections, is, tve believe, a 
nevo departure. — ED. 



THE CONCRETE INSTITUTE. 

THE APPLICATION OF CONCRETE IN MODERN 

SANITATION. 

By HENRY J. TINGLE, M.Inst.C.E. 

An exceedingly interesting and instructive Paper was read at the meeting of the 
Concrete Institute held on January fth on " The Application of Concrete in Modem 
Sanitation." The Paper was illustrated by photographs and diagrams, and, in addition, 
there was an Appendix dealing with the manufacture of concrete tubes. 

We give below an abstract from the Paper, together with a short resume of the 
discussion which followed. 

Introduction. 

The term " Sanitation " is capable of a wide interpretation, but for the present 
purpose it is proposed to limit its definition to Works of Water Supply, Main Sewerage, 
and Sewage Disposal. 

Concrete has played its part in sanitation for many years, with more or less 
success, according to the skill of the designer and the quality of the materials and 
workmanship. The tendency in recent years has been to employ concrete more and 
more, and this tendency in the future is certain to extend its use in directions where 
now it is scarcely applied. 

There is no doubt that sanitation works have been peculiarly affected by the 
attitude of the Local Government Board towards reinforced concrete, as such works 
are generallv undertaken by local authorities, who have to obtain the sanction of the 
Board to the raising of a loan for the amount of capital expenditure, or else to obtain 
Parliamentary powers by means of a Private Act. 

Doubtless in the early years of reinforced concrete the Board were well advised 
to act cautiouslv in the matter of sanctioning loans for the use of a combination of 
materials of which, in this country, there had been scarcely any experience, either as 
to its suitability or as to its life in sanitation works. 

With the experience that has now been acquired relating to the behaviour of rein- 
forced concrete that is constantly in contact either with water or with sewage, it is 
permissible to hope that the time' is not far distant when the Local Government Board 
will reconsider its attitude towards this material, and in cases where it is prop 
to make use of it will sanction loans on more favourable terms as to the period of 
repavment than those now in force. 

Concrete has been and now is extensivelv employed in the construction of reser- 
voirs, sewage tanks, filters, aqueducts, and water towers. 

n 9; 



THE CONCRETE INSTITUTE. [CONCRETE] 

Sewerage Work. 

Mass concrete has been largely used in the construction of sewers of 4 ft. diameter 
and upwards. It is moulded in the trench and supported by centering until set. 
Elliptical sewers are also constructed in this manner. In recent years reinforced 
concrete has been employed for sewers of both types, the mixture being sufficiently 
stiff to admit of ramming. 

Concrete tubes have been extensively employed in main sewerage work for many 
years past, being supplied ready for use by firms who have taken up their manufacture. 

Concrete tubes, unless strongly reinforced, should be laid on a concrete bed not 
less than 6 in. in thickness, and the concrete be brought up round the tube as far as 
the- springing. By the omission of this precaution many failures have occurred. In 
tubes liable to internal pressure the concrete should entirely surround them. 

The tubes have ogee, rebated joints, which are luted with cement and the inside 
pointed up. 

In a paper read by Mr. E. J. Elford, M.Inst.C.E., on June 6th, 1914, before the 
Institution of Municipal and County Engineers (vide Volume XL. of Proceedings), he 
describes the method of jointing concrete tubes laid in tunnel at Southcnd-on-Sea. The 
following extract from his paper gives the particulars : — 

" The socket and spigot were- so designed as to provide when placed together an 
annular space within the joint of about | in., and the specification required the con- 
tractor to lav the tubes with dry, clean joints, fill in solidly with concrete on the 
outside, and afterwards to make the joints by first sealing the interior with an 
expanding steel and rubber ring, and then forcing Liquid cement into the annular 
space through a hole in the ring at the side or invert. A second hole was to be 
provided at the top of the ring as an air vent, and this was to be left open until 
the cement began to flow out, after which it was to be plugged and the cement forced 
in until the joint was solid." 

The joints were quite satisfactory. 

Concrete tubes are manufactured on the " Jagger " system without ramming the 
matrix. The moulds are placed on a table to which a motion is imparted, described 
as " a horizontal vibratory movement combined with a vertical oscillation accompanied 
by a suddenlv arrested rocking movement which might be expressed as intermittent 
gliding shocks in quick rotation." The mixture is fed into the moulds, and the effect 
of the movements of the table is to cause the aggregates to settle down into a compact 
mass, without stratification, before the initial set of the cement occurs. It is also 
<-'.a;med that all voids disappear. '1 he presence of reinforcement does not interfere with 
the solidification of the concrete. 

In bad ground it is advisable to strengthen the concrete under the tubes by 
inserting reinforcement therein, thus forming a raft foundation. 

In some instances artificial means an- adopted to hasten the setting of the 
com rete while the tube is in the mould by exposure to hot air, with a view of 
releasing tie mould-, more quickly. It is claimed that the precautions taken during 
this process prevent any weakening of the resisting power of the concrete. It would 
appear that this is a case where investigation is required to ascertain more definite 
information. 

For sewers, the tubes are usually 3 ft. in length, and are sometimes slightly 
reinforced by the insertion of three rings of steel \ in. diameter, spaced about 12 in. 
apart. The joints in the rings are welded. There .are no longitudinal nor spiral 
rods. It is found that this simple type of reinforcement gives to the tube increased 
resistance to crushing. 

Tubes of the above type are very suitable for sewers, but are not adapted to with- 
stand high Internal pressure nor shock from moving columns of water. 

Tube- are made capable of withstanding high internal pressure, and <>f resisting 
water hammer. They are constructed with various systems of reinforcement, and are 
in use in Great Britain and more generally abroad. It is not possible to refer to all 
the systems of reinforcement adopted. Generally they consist of various combinations 
ol helicals and longitudinals, with the addition in some instances of circulars. 

The " Bonna " system goes a step farther, and is essentially a thin steel pip<> 
strengthened ^n<\ protected, externally and internally, by reinforced concrete. The 

96 



fj,Ct>NM'kM)lTiyNAI. 
lAuNQINhl W1NO — , 



CONCRETE IN MODERN SANITATION. 



internal reinforcement Is nol taken into consideration in th<- stress calculations, but 
its presence is necessan to support the interna] concrete. The dimensions o\ the 
cruciform steel b.n forming the helicals, and the distances ol the helicals from one 
another, togethei with the thickness ol the concrete, var) according to the dian 
of the pipe and the pressure to be resisted. 

lit- pipes are frequently manufactured on the s iie oi the works where the) are 
lo be laid. The) are usual!) [o ft. in length, and have been made from io to 7S in. 
in diameter. In one instance, al Rio Soza, in Spain, two syphons, each 12 ft. <> in. 
diameter, were laid und 1 two canals. 

The " Siegwarl " reinforced pipes •"' , ' constructed as follows : A steel core is 
revolved whilst concrete is applied l>\ machiner) until the required thickness is 
obtained. Steel wire is then wound b) the same machine spirall) over the concrete, 
in one ov nunc layers as required. The assembled longitudinal rods arc slipped over 
the spirals, and further concrete applied by the machine until the pipe is finished. 

These pipes are made 15 ft. long for diameters 12 in. to [8 in., and 12 ft. long 
for larger diameters. They have been used for water mains in Cairo, Zurich, Italy, 
and as a pumping main at Grays, Essex, the pressures being from 20 lb. to ioo lb. 
per sq. in., and have been tested at the Grays works to 300 II). per scp in. 

Both socket and spigot pipes, and butt-end pipes, with reinforced collars are made. 

Concrete tubes used as sewers may suffer damage from liquids being discharged 
into them at high temperatures, also by the discharge of acids. Instances have been 
recorded where concrete Iras perish: d when in contact with sewage. 

In the great majority of cases concrete suffers no damage by contact with sewage. 
Still, under certain conditions the lime in the cement may be attacked, and, as far as 
is possible, precautions; should be taken to prevent such conditions arising. Further 
investigation is needed to ascertain why concrete occasionally disintegrates when in 
contact with sewage. 

Manholes, Water Tanks, and Cesspits. 

Concrete tubes are constructed to form manholes, water-tanks, and cesspits. 

Messrs. Sharp, Jones adopt the following method for manholes : The foundation 
block is of concrete, made in one piece, with the inverts moulded, for the main 
sewer and the branches joining the same. It is lowered into the trench by the 
aid of ring baits, then the tubes forming the chamber are added, and as many feet of 
tubes forming the shaft as are required. Foot irons are provided. The shaft is covered 
with a special block of concrete, which carries the iron cover and frame. 

Sewers, reservoirs, manholes, vie, are constructed with moulded blocks of 
concrete which an' supplied by various manufacturers. 

The Dean Stone Co., of Devonport, manufacture blocks from crushed syenite 
obtained from the company's quarries at St. Keverne, Cornwall, and Portland cement. 

Straight and angle blocks are made for reservoir construction. The blocks are 
4^ in. thick and have iA in. hole and frog. They are 1 ft. in height, .and of varying 
lengths to admit of breaking joint at each course. The bottom course is made stronger, 
the blocks radiating from 4^ in. thick at the top to 9 in. at the bottom, with a special 
4 in. base, with groove to pin in the floor paving blocks. Liquid grout, composed, of 
one part cement to one part of fine-sifted crushed syenite, is, when the wall coursing 
is in position, poured down the 1^ in. hole, which it fills together with the frog 
underneath. 

Concrete blocks are also made by the above-mentioned firm to provide a bearing 
under each joint of an ordinary stoneware pipe sewer. When the pipes are in position, 
liquid cement is poured into the opening left between the outside of the pipe collar 
and the block, until the cement stands nearly level with the upper surface of the block ; 
by this means a good bottom joint is made in the sewer. 

The following instances within the author's experience are given as illustrating, 
in greater detail, the application of concrete to sanitation works : — 

Failure and reconstruction of concrete-covered reservoir. 

Temperature cracks in concrete reservoir wall. 

Ejector chamber in concrete with steel-plate lining. 

Concrete mole forming sewage outfall into sea. 

Circular hydrolytic tanks in reinforced concrete. 

n 2 97 



THE CONCRETE INSTITUTE. [CONCRETE 



Failure and Reconstruction of Concrete-covered Reservoir. 

This reservoir was constructed in concrete in the year 1S89, and stood for two 
vears when the failure occurred. The internal dimensions were : — 
East to west ... ... ... 112 ft. 3 in. 

North to south ... ... ... 79 ft. 6 in. 

Capacity ... ... .. ... One million gallons. 

1.' vel of invert of overflow ... 18 ft. 10 in. above floor. 

The reservoir was divided into two parts by .a longitudinal central division wall 
from east to west, and into five bays by four transverse walls from north to south; 
all the interior walls had arched openings. The bays were roofed in by concrete arches 
springing from the east and west walls and the transverse walls. 

Ample ventilation was provided by ten ventilators in the roof, each 18 in. in 
diameter. The roof was covered with soil to a depth of 2 ft. over the crown of the 
central bay, and 1 ft. 6 in. over the outside bays. 

Tin- reservoir was partly in and partly out of ground, the floor line being about 
11 ft. below ground level. The subsoil was clay, with a pot-hole of gravel in the east 
bay, in which was a weak spring of water. Earth banks, with slopes varying from 
It, to i, to i to i, were placed round the walls where out of ground. 

The walls were without counterforts. The south wall was strengthened by the 
addition of three valve chambers. 

The floor was 2 ft. in thickness throughout. 

The thickness of concrete in the arches was 1 ft. at the crown and 1 ft. 3 in. at 
2 ft. from the springing. 

Water was pumped into the reservoir through a rising main 10 in. in diameter. 

The concrete used in the work was composed of I names ballast and Portland 
cement specified 6 to 1 mixture. It was, on examination after the failure, found to- 
be dense, hard, and well set, except in the part of the floor over the pot-hole, and 
great difficulty was experienced when the repairs were effected in cutting the benchings 
in the undamaged portions of the walls to receive the new work. The interior surfaces 
of the exterior walls were rendered in cement. 

For some days prior to, and on the day of the failure, continuous pumping into 
the reservoir had been in operation. 

The reservoir collapsed suddenly without any previous signs of weakness having 
been detected, the west wall breaking away from the arch, the north and south walls, 
and the central interior wall. 

The failure was due to fault}' design, coupled possibly with over-pumping. 

The repairs consisted of reconstructing the east and west walls in brickwork and 
cement stepped into the undamaged lower portions of the original concrete, with the 
addition of concrete counterforts extending the full depth of the walls. Counterforts 
were also put into the north and south walls. The interior walls, where fractured, 
were reconstructed in brickwork, and brickwork rings, supported on brick piers, 
turned under the .arches over the openings. The east and west roof arches were 
reconstructed in brickwork and given 4 ft. rise. The .adjoining arch to the west arch 
was strengthened by five brick arches turned under it. The concrete over the pot-hole 
was taken out and fresh concrete put in, the spring being drained clear of the site. 
The slag layer was removed. The overflow was reconstructed with <asv bends, and 
an electric tell-tale connected in the pump-house. 

Since reconstruction the reservoir has been, and now is, in continuous use, 
without needing repair. 

Temperature Cracks i\ Concrete Reservoir Wall, Hadham. 

This reservoir was constructed in the year 1005. Depth of water, 11 ft. Subsoil, 
boulder clay. The floor of the reservoir was (> ft. below ground level, and the root' and 
sides were covered by earth, except for a length of 10 ft. on the south-east wall, where 
the outer face of the wall was exposed to allow oif access to the valve chamber, which 
was sunk into the ground and extended outwards from the lower portion of the 
M servoir wall for a distance of y ft. The chamber was covered with York stone about 
6 in. above ground level, therefore for this length of 10 ft. the reservoir wall, for S ft. 

98 



jfc|SS|gjgg9 CONCRETE IN MODERN SANITATION. 



deep measured from the top, was exposed to the atmosphere, and foi the bottom 5 It. 
was protected somevi ha1 l>\ the stone covei ing to the chamtx 1 . 

The reservoii was entirelj in concrete, except that brick piers were used to earn 
the rolled joists supporting the root arches, and these arches had a 4-) in. ring of 
brickwork under th*' concrete. 

The concrete was 6 to 1 l>\ measure of Thames ballast and Portland cement. The 
materials were turned twice <li\ and three times wet. The walls were 3 ft. <> in. 
thick al the bottom and 1 ft, 8 in. at the springing <>f the roof arches. 

The interior faces of the walls were rendered. 

In the latter pari of August, [911, it was reported cracks had developed in the 
south-east wall both inside and outside the reservoir. On examination it was found 
that the rendering on the inside face was cracked in several places along its entire 
length, and that small cracks had formed in the concrete on the outer face whore 
exposed. Also the portions of the rendering on the north-east and south-west walls 
adjoining the south-east wall were cracked. On cutting out the cracks on the outer 
exposed face they were found to penetrate into the concrete .about i\ in., and thos<- 
inside about 2 in. No signs of settlement could be detected by leveRing. 

In October the cracks were cut out and made good, and have not since reappeared. 

Ejector Chamber in Concrete with Steel-plate Lining, Seaford. 

This chamber was constructed on JOw-lying land situated 200 yards from the sea. 
The subsoil was rock chalk, which as the excavation proceeded was found to be 
fissured, the subsoil water being in connection with the sea. 

The original intention was that the chamber should be square on plan and of larger 
dimensions than the circular one actually constructed, hence the excavation was taken 
out rectangular, 19 ft. by 16 ft., the depth being 16 ft. below ground level. 

'Idle construction of the chamber was carried out in the following manner : The 
bottom of the excavation was covered by ballast 1 ft. in thickness to allow the water 
to reach the sump, which was sunk outside the excavation. Planks 10 in. by 5 in. 
were placed 2 ft. 9 in. centres in the ballast, so that, their upper faces were level with 
the top of the ballast. On these was laid a close-boarded platform 15 ft. by 15 ft., 
composed of q in. bv 3 in. deals. This platform was strutted down to resist the water 
pressure underneath until sufficient concrete was laid to resist the same. 

The circular tank rested on the platform, and was composed of riveted plates y (1 in. 
thick, stiffened by angle and T-irons ; the internal diameter being 12 ft. 9 in. and the 
height 8 ft. 6 in. The tank arrived on the work in six .segments, which were bolted 
up in situ. 

The bottom halves to which the side walls for a height of 1 ft. 6 in. were riveted 
were placed in position and bolted up; then the remaining segments were bolted on, 
bag concrete being brought up round the outside to the level of — 2'6 ft., after which 
mass concrete was continued up to the top of the chamber, the minimum thickness of 
the surrounding concrete being 2 ft. 

The bottom plate of the tank was covered by concrete 2 ft. thick, in which two 
cast-iron trays were embedded, on which the ejectors were placed in order that their 
weight might be distributed. The interior of the tank was lined with 14 in. brickwork. 
A collar joint of 2 in. of cement was formed over the bottom and the sides, and the 
tank was covered with reinforced concrete, in which a manhole was provided for 
access to the chamber. 

The concrete was composed of 200 lb. cement to 55 cu. ft. of sand and 11 cu. ft. 
of ballast, or 1 : 2% : 5 mixture. 

The work was satisfactorily completed in six weeks after the segments of the 
tank were delivered on the ground. 

Concrete Mole eorming Sewage Outfall into Sea, Seaford. 

This outfall consisted of a concrete mole in which two lines of cast-iron pipes 
were embedded. The site was an oj>en bay in the English Channel, exposed to the full 
force of the south-westerly and south-easterly gales. 

For a distance of from So vds. to 100 yds. from the sea wall the foreshore is covered 
with beach, and beyond this distance with a layer of sand about 2 ft. in thickness, 
under which is rock chalk. 

99 



THE CONCRETE INSTITUTE. [CONCRETE] 

An outfall of iS-in. pipes had been in existence at this spot for many years, and 
extended originally for a length of 83 yds. In 1901 it was carried a further 67 yds. 
bv 24-in. cast-iron pipes. The pipes were held in position by oak piles driven into the 
solid chalk some 3 ft. deep, with oak cross-pieces to which the pipes were slung by 
iron straps. 

In the spring of 1909 the travel of the beach over the top of the iS-in. pipe had 
worn a hole in it, through which beach gained access to the inside of the pipe, block- 
ing it up. The head of sewage thus engendered burst the weakened pipe. 

This burst took place at 81 yds. from the sea wall, where the beach ends and 
tin- sand is uncovered. Temporary repairs were effected and the pipes cleared. 

Application had been made to the Local Government Hoard to re-sewer the town, 
and to extend and duplicate the outfall. 

The contract for the work was commenced in the autumn of 1910, but for some 
time very little progress was made with the more difficult portion of the outfall. 

The work was done as tide work at spring tides, and even then it was not possible 
to carry it on unless the sea was calm; in addition considerable damage to plant and 
concrete was occasioned by gales. The outfall was completed in August, 1913. 

The whole outfall has stood the winter gales well, the concrete being sound. In 
places several bags were damaged, but have been made good. 

The concrete was 1 : 2 : 4 mixture, mixed dry by hand, placed in the work dry, 
and wetted bv the percolation of the sea water. The cement was burnt in rotatory 
kilns, ground all to pass 76x76 mesh, and residue on 180 x 180 not to exceed 10 per 
cent. ; initial set not under 30 minutes, final set not under 5 hours nor over 10 hours. 

Although not connected with concrete, it may be of interest to mention that the 
2-in. deals used in the timbering round the concrete were attacked by teredo worm, 
and rendered utterly useless in under 12 months' exposure. 

Circular Hydrolytic Tanks in Reinforced Concrete. 

These tanks are designed and are about to be constructed for dealing with sewage 
on the Travis Hydrolytic Tank system. 

The reinforcement is " Indented " bars, the stresses being limited to 16,000 lb. 
per sq. in. The concrete is 1:2:4 mixture. The shingle or broken stone is specified 
to pass through : , ! in. square mesh, and retained on f\ in. The cement is to be burnt 
in rotatory kilns and to comply with all requirements of the latest British Standard 
Specification for slow-setting Portland cement, the quantity of cement in the mixture 
to be determined by weight. The .stresses in the concrete are limited to 600 lb., and 
in direct compression to 500 lb. per sq. in. 

The tank is divided into various compartments by concentric walls, and by radial 
division walls. 

DISCUSSION. 

The President, in thanking Mr. Tingle for his Paper, said it was one that was likely to 
be extremel} u -< f u 1 to any of their members engaged in municipal engineering. 

The " Bonma " pipe referred to by the author was exposed to currents of hot air to hasten 
ill-- setting, but the experience of most architects and engineers was that reinforced concrete 
required some protection from hoi air, such as placing a moist surface over it, etc., and it 
would certainly appear thai they were sacrificing the strength of the pipes in order to shorten 
the time. 

A cruciform steel "ha r was employed in the " Siegwart " pipes for forming the helicals, 

hut lie preferred the round or square bars. 

Anyone who was in the habit of designing arches amd abutment walls would at once 
decern the reason for the failure of the concrete-covered reservoir; there was not sufficient 
resistance in the abutting walls they were hound to fail. In his opinion, when filling in the 
earth covering over reservoir arches, it was desirable, as far as possible, to begin at the ends 
of the arches and carry it carefully along, so that the thrusts were balanced all the way 
through and a uniform loading was obtained. 

Mr. T. ./. Moss - Flower, Assoc M.Inst. C.E., thought thai the ejector chamber which was 
put down on the sea shore was a rather expensive method of construction, and suggested that 
it would have been cheaper and more expeditious to have put in cast-iron tubing. 

Regarding the sewage outfall, he asked how long an interval was allowed to elapse 
between putting in the concrete and the turn of the tide. Mis experience in close-boarding 
100 



[^SraASlK^] CONCRETE !N MODERN SANITATION. 

tin- sides ni the trenches, putting in the concrete, .in<l then covering, the boards over, bad not 
been so successful as the lecturer's; the watei got in and practical^ destroyed the concrc 
He agreed entirelj with the Prcsidenl that the design ol the rescrvoh d< cribed wa 
that n must fail. When there was .1 greater thrust on the outside it might be bettei to have 
the batter on the inside, but Ins opinion certainlj in< lined to its being on the outside whi 

possible. 

The action of the* Local Governmenl Hoard wi li regard to the period oi repaymenl ol 
loans where reinforced concrete was concerned had compelled bim, in the interests ol his 
clients, to go in for massed concrete. The Board, however, in dealing with publii money, had 
to allow a large factor of safely, and he considered that from that standpoint then action 
had been quite justified so far there was satetj in going slowly. In reinforced concrete on< 
had to deal with the human (dement, and unless that were carefully looked after datngei 
would creep in. 

Mr. I). B. Butler, Assoc. M. Inst. C.E., said their thanks were due to Mr. Tingle because 
his Paper was largelj based on personal experience. 

Replying to Mr. Moss Flower's defence of the Local Governmenl Hoard, his own experi- 
ence was that, provided reinforced concrete was properly made, the contact of water should 
it get in to a slight extent— with the lime would form an alkaline which would act as a 
preservative to the reinforcement. 

Mr. J. O. Sharp (Messrs. Sharp, Jones and Co.) said he found the lecture verj 
interesting, as concrete was quite the earliest material he had to deal with. In the old days, 
concrete was regarded as a coarse material, to be used in bulk, and not for such delicate 
things as drain pipes, etc. 

Concerning the- old tests of concrete pipes made of broken stoneware, the quant it. \ ol 
this latter material available at the present day was practically nil. When obtainable, it was 
a most excellent aggregate; but even in those far off days, with a little trouble, it was possible 
to obtain a good cement, although there was no demand for it. 

He concurred with Mr. Moss- Flower's views respecting loans. People inquired why the 
Local Government Board did not follow the example of the Hoard of Works, the Admiralty, 
and other Government Departments, in regard to the use of reinforced concrete. His answer 
to that was, the Local Government Hoard had to sanction loans which would be expended under 
the supervision of local authorities, and the officials of local authorities were not always men 
of the wide experience of those in Government Departments, the result being that adequate 
supervision, which was most essential, was not obtained. 

In conclusion, Mr. Sharp emphasised the value of finely ground cement. 

Mr. S. Bylander inquired what provision was made at the joints in the reinforced con- 
crete pipes to take up the axial force produced by the pressure of water. He had not been 
able to discover any method himself for keeping the two pipes together. 

Mr. Sharman (Messrs. John Ellis and Sons, Ltd.) was surprised that so little had been 
said that evening about the importance of the aggregate in which the cement was mixed. He 
would like to have some expression of opinion from the lecturer as to the difference between 
the pot aggregate and the granite aggregate. The speaker concluded by referring to some 
tests he had made with granite sand, to the same specification as Leighton Buzzard sand, and 
said that the results obtained proved to him that even more important than the cement was 
the question of the aggregate, to which more attention should c ertainly be paid in the future. 

Mr. Alan Graham, A.R.I.B.A., said that more was to be learned from failure than 
from success, and for that reason they ought to be grateful to Mr. Tingle for the instances 
of failure which he had given. 

The President had asked why cruciform bars were used instead of round or square. The 
former were employed in order to place the value of the steel at its right position. The 
arm of the cross was greater in the upper bars, which performed the double work of acting as 
helical reinforcement and as stirrup or shear members. 

Mr. Robert N. Sinclair, MCI., referring to the reservoir where the crack appeared 
on the outside of the wall, said he was interested to see the way in which the difficult) was 
overcome, but he thought it would have been impossible in the case of a long wall. As a 
rule, the crack went right through, and whatever was done in the way of cutting out and 
repointing would be quite useless when the temperature varied again. 

On the motion of the President, a hearty vote of thanks was accorded to Mr. Tingle for 
his Paper. 

MR. TINGLE'S REPLY. 
Mr. Henry Tingle said the President had referred to a statement in the Paper that 
concrete should be machine mixed. By that, of course, he meant that it should be mixed in 
batches, and not continuously. The statement referring to hastening the setting of the con- 

IOI 



THE CONCRETE INSTITUTE. [CONCRETE} 

crete by exposure to hot air did not apply to the " Bonna " pipe, or any other pipe — it was 
quite general. At the same time, he would like the Institute to take the matter up, and see 
what was the real effect of this treatment on concrete tubes. 

The President's query re the cruciform form for reinforcement had been answered by 
Mr. Graham. 

He could not agree with Mr. Moss-Flower that cast-iron tubing would have been cheaper 
for the ejector chamber. They had received estimates for cast-iron tubing, but had chosen 
the method adopted. The same gentleman had asked how soon the tide followed the laying 
of the concrete. As soon as the water began to get to the level of the top boards they were 
closed, the water came through almost immediately, and work had to be suspended for perhaps 
two or three months until they had a quiet sea. 

He entirely endorsed the views of Mr. Sharman concerning the great importance of the 
quality and grading of the aggregate 

The first reservoir referred to in the Paper was undoubtedly a failure, but the second was 
a failure only to the extent that, during a very hot summer, slight cracks appeared in the wall 
that was exposed to the sun — no water was lost, so he hardly considered it a failure. He men- 
tioned it as showing the temperature stress where one side of the reservoir wall was heated to 
a temperature of perhaps 130 degrees, and the other, being in contact with water, had a tem- 
perature of only 55. Had it been a long wall it would probably have failed altogether; 
the method adopted prevented it from cracking right through. He agreed with Mr. Graham 
that the reservoir failed owing to the fact that the wall was not strong enough to withstand the 
pressure of the arches. 

The meeting shortly afterwards terminated. 



I 02 



g 



„CONMVUCTIONAL 
KNCilNt.t-KlNli — , 



REINFORCED CONCRETE IN CHINA 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information "will be presented of new works in course of 
construction or completed, and the examples selected ivill be from all parts of the world. 
It is not the intention to describe these works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea which served as a basis 
for the design. — ED. 



REINFORCED CONCRETE BUILDINGS IN CHINA. 

A r the present time, when considerable efforts are being made to extend the fiefld of 
our commercial operations, especially in China, where there are extensive openings for 
reinforced concrete, and where German business activities have been very considerable, 
it should he interesting to note that in spite of the enormous 'distance between England 
and China it has been possible to erect rapidly two large buildings in Hankow with 
bars which were all rolled ana prepared in our country. 

Several vears ago two large buildings, belonging respectively to Messrs. S. \Y. 
Litvinoflf and Co. and to The Trading Company, were destroyed by fire b) the Imperial 
Chinese Armv. When it became necessary to reconstruct these buildings Messrs. 
Hemmdngs and Berkley, architects and civil engineers of Hankow, gave pr< ference 




THi Burning of Hankow by ihe Imperial Armv. 



to reinforced concrete, and advised their clients to use this material for the reconstruc- 
tion of their buildings. The Coignet system, which has been described in our pages 
on many occasions, was adopted ; it has been extensively applied in Eastern countries 
on account of its simplicity in execution. Messrs. Edmond Coignet, Ltd., of West- 
minster, acted in the capacity of advisers concerning the use of their system, and all 
the bars forming the reinforcement were prepared and shipped by Messrs. The 
Whitehead Iron and Steel Co., Ltd., of Tredegar, Mon. 

103 



NEW WORKS IN CONCRETE. 



[CONCRETE 




View of Godowns of Messrs. Litvinoff and The Trading Co. in distance. 



It was, of course, due to 
the fact that the .architects had 
already a knowledge of the 
local conditions that it was 
possible to erect these two 
buildings in this material 
without any delay or diffi- 
cult}-, and entirely by means 
of native labour. 

The difficulties which had 
to be overcome by the archi- 
tects will be better understood 
when it is realised that in 
China work of this nature 
cannot be executed by local 
contractors, but must be ear- 
re d out by the architi ct or 
engineer, practically acting 
also in the capacity of con- 
tractor, arrangements being 
made for the execution of the 
work with a certain number 
( 'f small local contractors, 
«-;k b being in charge of a cer- 
tain portion of the work. 

All the window-sashes, 
the glass for same, and 
several other fittings were 
also s'-nt from England, and 
the two buildings were carried 
out simultaneously without 
any trouble whatever. 

It will be noticed thai 
these two buildings, the walls 
o! whii b w< re i onstru* U d in 
brick-work, have a very good appearance, which does c 
construction was comparatively simple. The buildings ; 
storage of tea, locally called " Tea Godowns." 

104 






SB 






M 



The Trading Company's G< 



down hi ILT in Kkiniok 


( 1 i) Concrete. 


redil to the archdte< 


-ts ; and the 


ire used for the pre] 


Kiration and 



d 



CONMUUCTlONAt 



REINFORCED CONCRETE IN CHINA 



The building foi Messrs. Litvinoff and Co. measures about 300 ft. long b> about 
55 ft. wide, and contains a first flooj and a second floor, calculated f<>i a superload <<l 
about 1'. cwt. There is also 1 flat roo] ovei the whole extent <>l the building. 

111! building Foi The Trading Cpmipanj is in 1 he shape oi a trapeze, having approxi- 
mately the Following dimensions: an average length <il about 140 ft. b\ an avei 
width dt about in 1 1 1 . 1 1 is composed ol three floors and m 11; it roof. 

The >i; 1 its in 1I1 esc buildings were also executed in reinforced concrete. 




Messrs. Liiyinoff's Godown built of Reinforced Concrete. 



IO5 



NEW BOOKS. 



[CQNCKETFJ 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books 'which have appeared during the last few months. 



Structural Engineer's Handbook. By Milo 
S. Ketchum, C.E. 

McGraw-Hill Book Co. Inc., London : 6 Bouverie St. 
89j pp. + xv. 

Contents. — Steel Roof Trusses and Mill 
Buildings — Steel Office Buildings — 
Steel Highway Bridges — Retaining 
Walls — Bridge Abutments and Piers 
- — Timber Bridges and Trestles. — Steel 
Bins — Steel Grain Elevators — Steel 
Head Frames and Coal Tippers 1 — 
Steel Stand Pipes and Elevated Tanks 
on Towers — Structural Drafting — 
Estimates of Structural Steel — 
Engineering Materials - - Structural 
Mechanics — The Design of Steel 
Details. 

This volume contains data for the design 
and construction of steel bridges and 
buildings, and much time and labour must 
have been expended by the author in its 
preparation, as it contains numerous draw- 
ings and tables, each of which represents 
a considerable amount of work. The 
author himself states that the book is the 
result of many years' work, and it is 
intended as a working manual for the 
engineer rather than as a treatise for the 
use of untrained students. The various 
standard sections and details which are 
given are based on American practice, and 
these will possibly not be in all cases of 
the same value to engineers in this coun- 
try as they will be to American engineers, 
but apart from this then- is so much valu- 
able information throughout the volume 
that it should find a place on the bookshelf 
of everyone engaged in structural design. 
The calculation of stresses has only been 
briefly considered, and then only in such 
cases a. are not generally covered by text 
'nooks, and several standard specifications 
for materials and workmanship are given 
that are not readily available to | he reader 
from any other source. 

The diagrams used throughout are very 
clear and Satisfactory and the tables are 
well arranged. Tables of logarithms, 

junction^ of angles, and tables that are 
easily available have not been included. 

The explanations and text generally are 



very clear and concise, and a practical and 
theoretical knowledge is displayed by the 
author which renders the descriptions 
valuable and interesting. Wherever 
possible, typical details are given of work 
actually executed, as distinct from 
theoretical matter prepared especially for 
the ; book, but many of the tables are 
original and have been calculated and 
arranged in a distinctive manner for this 
volume. 

The author states that he will appreciate 
notices of errors in order that they may be 
rectified in subsequent editions, and we 
notice that on page 548 the radius of gyra- 
tion of a rectangular section is expressed 
as o'28ga, instead of 0*280/*, this being 
obviously a printer's error. 

We have no hesitation in recommending 
the volume to all engineers, a ( s we feel that 
it will prove useful to all those who acquire 
it .and be a welcome addition to any 
library. 



Concrete and Steel Construction. Part I.— 
Buildings. By Henry T. Eddy 6 C. A. P. 
Turner, Minneapolis, pp. 438 + xv. 

Contents. — Concrete and Steel — S'labs — 
Beams — Beam Action and Slab Action 
— Theory of Flat Slabs — Computed 
Stresses and Deflections verified by- 
Test s — Moments with Two-way and 
Four-way Flat Slabs — Reinforced 
Concrete Columns — Foundations — 
Elements of Economic Construction 
and Cost of Reinforced Concrete 
Work— Fireproof Properties- — Protec- 
tion of St end — Finishings- Artistic 
Treatment —The Execution of Work. 
This is a treatise upon the elementary 
principles of design and execution of re- 
inforced concrete work in buildings, and it 
is illustrated throughout by numerous 
drawings and photographs. Although 
various patented and unpatented types of 
construction have been dealt with, the 
majority of the text and illustrations deal 
with examples of the Mushroom system, 
in which the authors have a particular 
interest. The volume is well written and 
arranged, and the matter is expressed in a 



1 



~ OONM VmTION A I | 
t.N(.IM.l k'INt. —J 



NEW BOOKS, 



mannei which renders it eas) to undei 
stand and interesting to i ead. 'I he 
theoretical design of the various members 
of ;i reinforced concrete structure are con- 
sidered fullv, commencing with those 
elementan principles upon which the 
-I - ign is based, and the formulas recom- 
mended b) the Joint Committee of the 
American Societ) of Civil Engineers on 
Concrete and Reinforced Concrete are 
given, together with the standard notation. 
A great deal of text is devofa d to the theory 
as affecting the Mushroom system, and 
comparisons are drawn by the authors to 
show in what manner superiority is 
claimed for this system as compared with 
the beam and slab method of construction. 
There is no doubt that a large amount of 
time and energy lias been spenit by those 
responsible for this volume in the prepara- 
tion of particulars and in Investigation, in 
order to put forward evidence in support 
of their contentions, and the matter pre- 
sented is both theoretical a«id practical in 
character. Several tots are described and 
illustrated, and many buildings actually 
executed in reinforced concrete are dealt 
with. 

The chapters dealing with surface 
finishes and the execution of the work are 
very interesting, and contain a great deal 
of information which should prove useful. 



Generalh speaking, the book is quiu good, 
and, although there is much which would 
only prove useful to anyone adopting the 
Mushroom system, there is also a great 
deal of matter which is worth while study- 
ing, and the authors hav< prepared the 
volume in a thorough manner which is 
commendable. 

Concrete Roads and Kerbs. 

Published by the Associati <l Portland Cemenl Manufat 
turns (1900) Ltd., Portland House, Lloydi 
B.C. 

The question of concrete roads is re- 
ceiving considerable attention at the 
moment, and therefore this pamphlet will 
doubtless be read with interest by those 
who are specially studying this important 
matter. It is illustrated, and contains ex- 
tracts from papers and reports presented 
at the International Road Conference held 
in London, and the Concrete Road Build- 
ing Conference held in Chicago. Then' is 
further reference to the experimental road 
sections now in course of construction at 
Gravesend, as also the road recently com- 
pleted at Chester. A chapter is also de- 
vot< d to concrete kerbs. The pamphlet 
should appeal specially to engineers and 
surveyors, who can obtain copies on appli- 
cation to the Publications Department of 
the above company. 



/o' 



CORRESPONDENCE. [CONCRETE] 

CORRESPONDENCE. 

Under this heading ive ini>ite correspondence. 



"The Use of a Tremie for Underwater Concreting." 

Sir, — Your last issue contained an article on the use of a tremie for under- 
water concreting, and I thought that my own experience during last summer with 
a tremie might prove interesting. 

The reinforced concrete abutment bottom slab of a concrete bridge across the 
Tweed, near Peebles, had to rest upon a 3-ft. thick mass concrete foundation, the 
bottom of which was 5 ft. below wat< r surface, and for 'depositing this the use of a 
tremie proved most satisfactory. 

A wooden tremie with parallel sides was first tried, but soon discarded, because 
the concrete, which was only just damp, arched across and made the combined weight 
of concrete and wetted wood too much for two men (more could not be employee! 
because of space) to lift. 

The local blacksmith was called upon to make a galvanised iron tremie with 
hopper head and fitted with handles, and it worked splendidly. 

Tremie. — The length was about 11 ft., including the conical hopper head, which 
was 30 in. across at the top, 12 in. high, and 6 in. where it joined the pipe, which 
was of that diameter at the top, but increased to 10 in. in diameter at the bottom to 
prevent the concrete arching, and which therefore allowed easy lifting. Two handles, 
one on each side at the mid-height, allowed one man to lift, while another handle 
near the bottom .allowed another man to guide the tremie and so spread the concrete. 
During the placing of the first layers a rope was run through this bottom handle, but 
as the concrete rose the man caught the handle by hand (it was placed 1 ft. from the 
bottom of pipe). The art is in maintaining a level surface to the concrete, thereby 
prev< nting rolling and loss of cement. 

The Concrete. — The concrete was mixed 1 : 2\ : 5 of gravel, and on pumping 
out the water it was found to be quite dense, and over an area of 27 ft. by 16 ft. 
an occasional turn with a diaphragm hand-pump easily kept the surface free of water, 
a flight pitch to a sump in one corner making this easier. The concrete was, as 
previously noted, mixed only just damp, and I would recommend that as little water 
as possible, consistent with easy movement in the tremie, be used for such work. 

The tremie was always kept half full, and only lifted about two or three inches for 
each half pailful of concrete added. 

In slowlv moving water a trumpet mouth to the lower part of tremie will greatly 

ct tie- concrete from action by water. 

H. C. Johnson, University College, Cork. 



108 



m 



ONS'IQXH I ION 
N(,IM I l-'INt 



S 



CONCRETE 1 /.'"' ',//> 



POPULAR USES. 

Under this heading it is proposed from time to time to present particulars of the more 

ropul.ir uses to which concrete and reinforced concrete can be put. -is, for Instance, in the 

construction of fa ttages, and farm buildings* >'•■ vious articles •unit /«• found (n our 

of December. 1912 ; January, March, July, October .mJ November, 1914) I 

January of this year, ID. 



SOME CONCRETE TROUGHS. 

I \ Amcrii a, on the farms, 
(.-oiicit i e trough's are more or less 
taking the place of i he wood 1 ) n 
trough, which has .'i compara- 
tively short life and soon becom< s 
leaky and dilapidat< il in appear- 
;iik e. 

There are many shapes and 
kinds of watering troughs. The 
most attractive in appearance is 
the circular trough, but this is a 
little harder to build than one of 
rectangular shape. The circular 
tank shown on this page was 
built by farm labour, and Is filled 
from a well by a pump operated 
by a windmill. 
The most common practice is to build circular troughs of monolithic- concrete, 
but blocks also may be used. One of our illustrations shows an excellent barnyard 
trough made of silo blocks, Laid up three courses above the foundation and plastered 
on the inside with rich cement mortar about i in. thick at the top and 2\ ins. thick 
at the floor level. Reinforcing rods were laid in the joints between block courses, 
and the trough has stood several winters without sign of injury. Plenty of reinforcing, 
a battered or sloped inside wall, and a rich concrete make a trough that will with- 
stand frost. 

Rectangular tanks are a little easier to build, especially if the farmer builds his 




Fir, . 1. A Concrete Field Trolgh. 




Fig. 2. A Circular Trolgh. 



IO9 



POPULAR USHS. 



(C ONCRETE) 




A Concrete Monolithic Field Trough. 



own forms. Fig. 4 is a good 
example of a rectangular barn- 
yard tank. Water froze solid 
during the first winter of its 
service, but the trough was not 
injured. The ice pushed upward 
without causing harm. 

It pays to cover stock troughs 
in order to keep out leaves and 
dirt and also to keep water 
warmer in winter. On a farm 
near Lake Beulah, Wis., are two 
covered concrete troughs, the 

smaller for horses and the larger for stock. The windmill pumps water directly into 

the larger tank, from which an overflow pipe fills the horse trough. 

Around the latter is a concrete apron to prevent the formation of a mud-hole. This 

is a very good practice, for otherwise the animals' hoofs dig up the ground around the 

tank and form holes in which 

water will stand. 

The horse trough was built 

later than the one for stock, and 

the illustration (Fig. b) shows it 

to have much smoother walls. 

It is possible to make perfect 

concrete work the first time, but 

generally the surfaces are cleaner 

and the corners more perfect 

after the builder has had a little 

experience. 

A still better form of cover- 
ing, and one that is specially 

suited to large tanks, is shown in 

Fig. 7. The tank is 10 ft. by 

30 ft. by 6 ft. deep. An arched 

concrete cover keeps out dirt and 

cold, and two wooden covers at 

the end protect the openings where stock is watered. To build the walls is a simple 

matter. The arched 'top is more difficult to construct, although one who has had a 

little experience with concrete need have no fear to attempt it. The concrete cover was 

build in three sections, 10 ft. at a time, and the forms used for the first section moved on 




Fig. 4. A Rectangular Stock Tank. 




Fxo. 5. A Drinking Trough <<\ Concrete Silo Blocks, plastered on the insidk 



I IO 



j iW.MUIIt'TIONA 
A 1 NQIM 1 l-'INt 



NJAll 



CONCR) ti TROUGHS, 




Fig. 6. Showing Covers for Concrete Troughs. 

after it had hard* ned. Thus only a small amount of lumber was necessary. Where 
a large storage tank is needed there is nothing better than this type. 

Often there is need of a smaller trough to be placed in a Held temporarily. This 
also can be built of concrete to advantage, as shown in Fig. i. They are 5 ft. long, 
2 ft. wide, 15 ins. deep, well reinforced, and stand on two cone-ret;- supports. The 
trough is piped to a pressure supply. 

A olean-walled water-tight drinking trough for stork is a source of permanent 
satisfaction to the owner. There is no calking of joints, for the concrete trough has 
no joints. There is no trouble from freezing, for a well-designed tank can freeze solid 
without harm. 

The above particulars and illustrations have been taken from the Farm 
Cement News, U.S.A. 




Fig. 7. Covered Concrete Water Supply Tank and Troughs. 



I I ' 



MEMORANDA 



OTjc^Te] 




Memoranda and Neivs Items are presented under this heading, with occasional editorial 
comment. Authentic neivs ivill be "welcome. — ED. 



Bristol Docks. — A tender has recently been accepted for the construction of a 
reinforced concrete wharf at the oil berth in the Western Arm of the Royal Edward 
Dock, Bristol. The tender was that of Messrs. W. Cowl in and Son. 

Belfast Harbour Equipment. — The new 120-ton crane which has just been brought 
into use at Belfast Harbour rests upon three concrete piers at an elevation of 47 ft. 
above quay level. The foundation of the main pier (which measures 40 ft. by 40 ft. 
at its base) has been carried up from a depth of 52 ft. below quay level, and contains 
4,000 tons of concrete. This portion of the work was carried out department ally by 
the Commissioners' employees. The total distance from the foundation level to the top 
of the jib of the crane when at its minimum radius is 204 ft — . about 20 ft. greater than 
the height of the larger of the two chimneys at the new Graving Dock. 

Alford. -At a recent meeting of the Alford Urban District Committee it was agreed 
to recommend the Count)' Road Hoard to erect a concrete bridge with a 13-ft. carriage- 
way over the Don at Drumallochie, the estimated cost being ,6*1,575. 

New Reinforced Concrete Bridges. — At a meeting of the Thames Conservancy 
li-t month provisional acquiescence was expressed with the plans for three new 
bridges across the Thames. One of these would be constructed across the river between 
Coring and Streatley. Plans were originally prepared two years ago, but had to be 
abandoned because it was found to be impracticable to construct such a bridge with 
approaches having a reasonable gradient to suit the structure. Consequently another 
pi m has been prepared, providing for a tresselled structure somewhat similar to the 
present bridge, but to be constructed in reinforced concrete. This design had been 
made the basis of the plan which had now been deposited. The Conservancy suggested 
a modification in the design, with the object of increasing the width of the waterway 
for navigation purposes. 

The other two bridges were to be built by the Reading Corporation over the river 
between Reading and Cavershain. The first to be built would be the De Bohun Road 
Bridge, which would be of reinforced concrete with a stone parapet. The design pro- 
vided for a bridge of single span with a width of [80 ft., and a maximum rise of 18 ft. 
above the normal level of the water. 

Concrete Tramway Sleepers. — We understand that the newer lines of the Berlin 
Tramways were from the .end of mjij to the middle of [913 supplied with about 25,000 
rein-forced concrete sleepers, and that some 8,000 sleepers similarly constructed were 
to have been delivered to the tramways in 1 <> 1 4. 

The Construction of p Slipway for Motor Boats. — Where a dry dock is not 
available the utility of a slipway is unquestionable, says The Motor Ship and Motor 
Boat, and it may perhaps nol be ouii of place to give a few details as to the construction 

of a workable s!ipw aw 

11m slip described here has been with a lew unimportant alterations constructed in 
India, and has worked satisfactorily for several years. 

When building a slipwa\ three importanl factors have i<> be taken into considera- 
tion tide, ground available, and depth of water at the lowest portion of the slip. The 
gradient can always be formed. 
1 1 2 



BgggBBggg MEMORANDA. 

In selecting the site i1 is best where possible i»> pitch on n position \\lnn the rivei 
shoals rapid h to aboul one fathom ;ii low tide. Having selected the site, th< qu< stionoi ii<l. 
nuis! be gone into, and foi the sake ol argument we will assume thai the localit) chosen 
is somewhere on the lowei reaches of the Thames, where the tidial difference is i.V, ft. 
.ii spring tides and 15 ft. .11 the neaps. Now the slip must be capable ol taking on a 
vessel ot at leasl 60 ft. in length and <> ft. draught forward, so that the lowei part «>i 
the gradient must, at, say, three-quarter flood, have a sounding of 6 It. plus the height 
of the slip carriage, and the higher part of the slip must terminate at least 0^ ft. 
above high-water mark. I'he extra 5 ft. is required foi drawing tail shafts, etc. As 
the gradient for convenient working should not be more than 1 in 15, it will be seen 
that the total length, allowing <> ft. clearance at the upper end for the winch gear, is 
360 ft. These figures can, of course, be modified 1>\ only docking at lull flood and 
working when tlu ebb has well set in. 

The length having been decided upon, a post should be driven in at high-water 
mark, with its end just level with the wafer, and another ~i It. above it, the top being 
4 ft. S 4-5 in. above the level of the high-water post. 

These two posts are standards for gradient hesides being checking points for length. 
Another post is driven in at the river end 280 ft. below the high-water post, and the 
high-water level should be marked on this. 

This post indicates the lower point of the gradient, and at very low tide should 
mark the edge of the water. If the soil is fairly stiff, such as good London day, it 
need only he removed for a distance of 2 ft. to 2 ft. (> in. below the gradient level, and 
the space filled in with concrete. This requires to be of very good quality immediately 
below the rails, hut need only he about a foot thick in between and at the sides. The 
width of the cutting should be about 20 ft. at the bottom and about 30 ft. at the top. 
This depends, of course, on the earth, as, for instance, should the soil be of a loose, 
sandy nature, the angle of slope must be much less than if of stiff or hard clay. 

The rails, which are preferably of the double-headed variety, should be of not less 
than 60 lb. weight and of the bull-head pattern. Old rails in good condition are quite 
serviceable for this class of work. The centres should not be less than 6 ft., and the 
best method of attaching them to the track is to have 12-in. oak baulks running longi- 
tudinally for the whole length of the track and Hush with the concrete surface. The 
chairs can be attached to these, .and the rails keyed in, in the usual manner. The 
outside edges of the baulks should be about 6 ft. 2 in. apart, and this will give quite 
room enough for the ordinary 14^-in. chair to be bolted on to them. On the inside 
of these baulks there should be another pair of baulks, 4 in. by 4 in., to carry the rack 
rails. These are to be not 'less than 4 in. wide, and should be bolted through by bolts 
in countersunk holes to the conereted-in baulks. To prevent any possibility of the baulks 
themselves slipping, anchor-spikes or Lewis bolts should be employed, these being 
embedded into the concrete for about 12 in. 

The 71 ft. of working section should have the banks well dressed and three flights 
of concrete steps on each side, about 2 ft. 6 in. broad. These are very useful to take 
the ends of struts and also to rest the shore ends of gang planks on when material is 
being taken on board or brought off. With the centre 6 ft. from the top end two 
recesses should be constructed in the bank about 10 ft. long and h ft. deep. These are 
to accommodate a pair of sheer legs for use in removing engines, etc., from the boat, 
and the sides, which max Ik 1 made vertical, can be bricked up. A nice finish to the 
whole (-(instruction is to brick or concrete the slope up for about 6 ft. and then dress 
the top down with coir to a depth of 6 in., finishing the surface off with expanded 
metal and cement 1 in. thick. This makes a very clean job, and the whole can be 
hosed down, ensuring freedom from dust when varnishing or french-polishing is being 
performed. 

Draining Land by Welts; Concrete Drain //ea</. — Draining agricultural and 
swamp lands by wells or vertical drains- -instead of by ditches and horizontal lines of 
lih has been done successfully in a number of cases throughout the Central Stales. 
The wells are sunk to reach underflow strata that will absorb or carry off water readily. 
Success depends largely upon proper knowledge of the geological conditions, and results 
are problematical when the drain-wells are sunk at random. 

The depth of wells is said to range from 20 ft. to 45 ft. It is claimed that one 
well will drain from half to three-quarters of an acre. 

"3 



MUMORAS'DA. 



[CONCRETE] 



The wells arc drilled with augers, pipe extensions being added to the shaft ot the 
auger as the depth increases. Through quicksand or soft clay, casing must be put 
in. A bucket to remove soft materials and a stone-picker to remove stones or small 
boulders will also be required. The nature of the materials encountered must be 
| carefully. The hole can be inspected by means of a mirror to ascertain the 
strata reached, etc. The diameter of the hole is usualh 8 in., to take a lining of 6-in. 
drain t : 

The drainage is taken from the soil, surface water being excluded. For this pur- 
| drain heads are made, which prevent the water from carrying soil into 



the pipe. The top of the drain pipe is 



ft, 



ft. below the 



surface of 
it the ground is excavated to a diameter of about 
\l ft., the lowest part of this hole being lined with stones or old brick to form a water 
chamber. Upon the 6-in. drain pipe is placed a collar, and this supports a grooved 
inner head surrounded by a sleeve or soil fender. The chamber is roofed with a cap 
After these parts have been assembled, the ground is filled in above the cap. 
When the ground becomes wet, the water seeps up under the chamber and siphons 
up under the fender, flowing over the top of the grooved inner head into the vertical 
drain.— Engineering News. 

PUBLICATION RECEIVED. 

The British Engineers' Association. — In our last issue (page 57) we made a short 

rence to Mr. Wilfred Stokes's speech regarding our foreign trade and the war. 

The above Association has now published the entire speech in pamphlet form, together 

with an article from the Engineer. The pamphlet is obtainable at 32, Victoria Street, 

S.W., price 6d. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum |-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 



The VICTORIA 



is built to last 



WRITE FOR CATALOGUE No. 29. 



THE 



T. L. SMITH Co. 

13, Victoria Street, S.W. 



"4 



PltJH>r men lion this hnirn.il 'inlwn taritinq. 



09 

O 

z 

5 

j 

5 

co < 
w 

LU 09 

z 
z < 

<s 

1 c/) 
o 

X 

III 



z 




CONCRETE 



Volume X. No. 3. London, March, 1915 

EDITORIAL NOTES. 



RURAL HOUSING. 

The problem oi erecting cottages at a reasonable cosl for the occupation of the 
working classes is one which has received a great deal of attention during recent 
years, and it is a question of much importance to a large section of the com- 
munity. The designer and contractor are affected during the ordinary course of 
their business ; the financier is concerned, inasmuch that he requires to see a 
satisfactory return on the initial outlay in any building - scheme, and the working- 
classes must be able to acquire dwellings the rent of which is within the limit 
they can afford to devote out of their wages. Man}- ideas have been put 
forward, and various materials and methods have been suggested and in some 
cases adopted, in the attempt to provide a solution of the problem ; but it is still 
extremely difficult to erect satisfactory cottages at a cheap rate. In many 
districts the bye-laws which govern the methods of building- are so rigorous 
and unreasonable that they hamper the development of schemes which would 
otherwise go forward ; and although we do not advocate the abolition of a 
proper control of all classes of building work, we do consider that a certain 
amount of judgment should be exercised and each case dealt with according to 
circumstances, and generally speaking the bye-laws in existence are antiquated 
and not applicable to modern work. 

At various times we have pointed out the possibilities of concrete for 
cottage work, and although it has not yet been tried on a very extensive scale, 
we are confident that it has a great future in this class of construction. In this 
issue we give details and description of some cottages which are being erected 
at Crayford, in Kent, and in this case concrete blocks have proved cheaper than 
brickwork, despite the fact that Crayford is a brick district and a brickfield 
actually adjoins the site; thus there is no question of bricks being unobtainable 
or even procurable only at a high price. If concrete can compete favourably 
with brickwork in a district such as this, it will be clear that a tremendous 
advantage will be shown in the majority of cases where cartage is an important 
factor in the cost. The work has been carried out during the worst months of 
the year for building, and yet it has been executed quickly and with satisfaction 
to all the parties concerned. The cheap price per cottage is all the more remark- 
able when it is considered in conjunction with the increased cost of materials, 

1 1 ; 



RURAL HOUSING. ICDNCBETE] 

and as materials are likely to still further rise in price, concrete should become 
more general in use, as in this form of construction there is only about one-half 
the cost of labour in laying the blocks as compared with brickwork, and less 
mortar is required. 

The strength of concrete and its lasting- properties are unquestionable, and 
it onlv remains for contractors to see that work of this kind is executed in a 
proper manner, and any prejudice would be removed from the minds of building 
owners, and its cheapness would lead to the adoption of concrete block con- 
struction for many housing- schemes. 

THE CONSTRUCTION AND PROTECTION OF BUILDINGS IN RELATION 

. TO FIRE. 

The Society of Architects were fortunate in the presentation of a most useful 
Paper by Mr. Alban Scott, their vice-president, whose subject was the Construc- 
tion of Buildings in Relation to Fire. 

In another portion of the current number we reproduce an abstract from 
this Paper, which should be perused with care, as being- eminently instructive 
and also valuable for reference purposes. 

It is obvious that in the development of fire protective construction concrete 
has already played a great role, and this rule is being- increased from year to 
vear. The excellence of concrete as a fire resistant, if proper aggregate be 
used and if properly applied, scarcely requires argument. But there is still 
an extraordinary amount of ignorance as to the nature of the aggregate, as to 
its size, and as to the thickness to which the material should be applied in order 
to be thoroughly efficient. 

One thing, however, i,s quite plain in the negative sense, and that is, that 
there is no concrete of such small fire resistance as concrete of Thames ballast 
or similar ballast, especially if the aggregate does not pass through a f-in. 
mesh and if it contains flints. 

Coke breeze aggregate is the mo.st valuable fire resistant of all, but unfor- 
tunately the purveyors cannot be sufficiently relied upon at all times to deliver 
it in a properly cleansed and washed condition, and if not properly cleaned it 
may contain chemicals that affect metal work. This has probably resulted in 
the somewhat short-sighted policy of the London County Council, and some of 
the institutions it has consulted, in desiring that coke breeze concrete should 
be avoided. 

What would of course be ideal, and what is now becoming common in 
the best American practice is, for the reinforced concrete work to be carried 
out in some one of the stronger aggregates, and that this reinforced concrete 
work should, particularly where used for column work, be protected by i \ in. 
or 2 in. of coke breeze or cinder concrete, which afford such an excellent protec- 
tive covering'. 

The whole subject matter is, however, one that goes too far to allow of its 
treatment In this place, but we are afraid that an extraordinary amount of 
amateurism still exists as to the pros and cons of the various concrete aggre- 
gates from the fire point ot view, based 00 opinion as distinct from facts, and 
until facts .ire given pre- eden< <• to opinions, a large number of blunders will still 
be made. 

1 16 



ff r CON5TB0 



EMGTNEEB1NG~ 



NEW EXCHANGE BUILDINGS, SWANSEA. 




Jim imp«m 




Finished Building, Exterior View. 
New Exchange Buildings, Swansea. 



THE 
NEW EXCHANGE 
BUILDINGS, 
SWANSEA. 



The buildings here illustrated 
afford an interesting example of 
the architectural possibilities of 
reinforced concrete, — ED. 



These important premises, which were formally opened in January by the 
Right Hon. Sir Alfred Mond, Bart., M.P., have been erected at a cost of about 
£. '30,00c upon the same site as the old Exchange Buildings stood. 

The old buildings, which formed the premises wherein met the men who 
transact the great bulk of the business of the important docks of Swansea, 




- LawTR-GPOVND-fLGDP- PL Ah ■ 

Fig. 1. 
New Exchange Buildings, Swansea. 



117 



NEW EXCHANGE BUILDINGS, SWANSEA 



IOONCBETEI 



were in an exceedingly dilapidated condition, having generations ago been the 
Old Burrows Chapel, one of the chapels associated with the Countess of Hunt- 
ingdon's Connexion. This site, on the corner of Adelaide Street and Cambrian 
Place, was originally a portion of the foreshore washed by the tide. 




SECTION AA 

Fig. 2. 



car" 




gECTlIW ]firjfj> 

Fig. 3. 
New Exchange Buildings, Swansea, 

After the removal ol the old premises and the carrying oul of the excava- 
tions lor the basemenl premises, ii was found thai the area of the site consisted 
largeh ol sand with a somewhal peculiar formation of clay ''pockets" here 
and there, 

i is 



i, I'ONM L'UO lONAll 
AF»(ilNhl.klN(. —J 



NEW EXCHANGE BUILDINGS, SWANSEA 



! lir .i»l »ption el reinforced concrete \\ ;i s considered to be necessan in crder 
i<> ensure .1 firm and solid structure, and the drawings show in general outline 
the arrangement <>l columns, concrete rafts and beams, 

The whole oi the foundations, stancheons, floors, beams, and lintels have 
been carried out in reinforced concrete, and the peculiar necessities of the 
accommodation required called for special treatment in reinforced concrete con- 
struction lor the purpose oJ carrying a portion <>l the three upper floors over 
the cent ral well ;u e.i. 

Tliis design, it will he noticed, provided the Large Chamber :>l Commerce 
Hall on the upper ground floor, hut ;it the same time permitted the planning of 

a double row of offices on three sides of the central area. 




Fig. 4. The Exchange Room. 
New Exchange Buildings, Swansea. 



The lower ground floor has been planned as extensive restaurant premises, 
the large dining-room being capable of accommodating about 600 persons. The 
floor is laid in Belgian marble tiles, and the reinforced concrete columns have 
been artistically treated by casing in beautiful figured Italian marble. 

The upper ground floor contains the Chamber of Commerce premises, the 
re 111 forced concrete cantilevers being artistically treated in fibrous plaster 
decoraiion, and the deep beams above being panelled ; there is also a post 
olhce, bank and office premises. 

The central hall for the use of members of the Exchange is centre lighted 
by means of a fine stained glass dome. 

The first, second and third floors contain some eighty offices. 



B2 



119 



NEW EXCHANGE BU1LD1XGS, SWANSEA 



[CONCRETE 



R£S~AYQAMT 




• vPPtR • GPOVfsiD < FlCDD- PLAN 
Fig. 5. 




flPST *'<° ^LCOHD-rLOOP- PLANS 
Fig. 6. 
New Ez< hangs Buildingsi Swansba. 



I 20 



/r OCMSTDUCITGNA] 



-NCJMKI PI Nli 



^ 



NEW EXCHANGE BUILDINGS, SWANSEA 



The main facades have been erected in unpolished Aberdeen ^ i «■ \ granite 
to the plinth level and above in selected Portland stone. 

The balustrading in Adelaide Street has also been erected in grey unpolished 
granite. 

Two press-button automatic passenger lilts arc provided for service to the 
various floors, -\^d other electric lilts for restaurant service, etc. 

The architect for the building was Mr. Charles T. Ruthen, Licentiate 
R.I.B.A., M.S. A., Swansea (to whom we are indebted for our particulars), in 
association with Mr. E. G. Allen, F.R.I.B.A. 

The reinforced concrete work was carried out by the Midland Counties 
Reinforced Concrete Co., of Birmingham, whilst the general contractors were 
Messrs. Henry Billing's and Son, Swansea. 

Amongst the subcontractors were Messrs. Henry Hope and Sons, Ltd., 
Birmingham, who carried out the heating work ; Messrs. Furneaux and Thomas, 
Swansea, were responsible for the electric lighting ; the lifts were those of 
Messrs Smith, Major, and Stevens, Ltd., Northampton, and the ironwork thaf 
of Messrs. Hart, Son and Peard, Ltd., London. 




Fig. 7. Restaurant. 
New Exchange Buildings, Swansea. 



I 21 



A STAXDARD SPECIF1CATIOX 



CONCRETE] 




A STANDARD SPECIFL 
CATION FOR REIN- 
FORCED CONCRETE 
WORK. 



The Science and Reinforced Concrete Practice Standing 
Committee of the Concrete Institute have been engaged in 
the preparation of a Standard Specification for Reinforced 
Concrete Work, and the results of their labours 'were submitted to the members of the Institute 
in the form of a Draft Report at the Fifty-Sixth Ordinary General Meeting on Thursday, 
February 4th, in order that they might have an opportunity of making suggestions and discussing 
the subject generally, previous to its issue in final form. We have been asked not to publish 
the specification at present, but in the following article 'tve give a feiv notes regarding same, 
together •with one or tvjo suggestions and a short account of the discussion which followed, — ED, 



There is undoubtedly a great need for a standard specification, and the Committees 
concerned in its preparation are to be congratulated for taking the matter in hand and 
producing what, in our opinion, is a very excellent result. It would be quite im- 
possible to put forward as a standard a specification which would be accepted by 
everyone concerned as ideal, because the interests of the different parties are so varied, 
and what would be considered as necessary by the architect would possibly be deemed 
excessive by the specialist. The great object to be kept in view is that the specifica- 
tion must be adequate and at the same time it must be fair to the contractor. If it 
is not adequate it will not ensure the client's interests being protected, and therefore 
it would not be generally adopted by engineers and architects; while if the conditions 
are irksome to the contractor, it will tend to increase the cost of the work without 
ne< essarily improving the class of work obtained. 

It is worthy of note that in presenting the Report Mr. E. Fiander Etchells, 
F.Phys.Soc, stated that on almost every single point of the specification most of 
the members of the committee differed, but they had endeavoured to make it a con- 
sistent whole, and to embody the ideas current among all engineers as good practice. 
'I his variation of opinion is unavoidable, and as the report represents a consensus of 
opinion, and is based upon good practice, the Institute can have every confidence with 
the specification as drawn up, and feel that a great benefit will be conferred on the 
engineering profession and contractors generally by the issue of such a specification. 

It is divided into two main parts, the first of which deals with the General Provisions 

and the second with Materials and Workmanship. 

GENERAL PROVISIONS IN THE SPECIFICATION. 
With regard to the former the items are few and of a general nature, as the 

general conditions of contract are specified to be those of the Royal Institute of British 

Architects, which is a satisfactory method, and there is only one item which is, in our 

opinion, quest ionable. 

This item i« No. ~|, which refers to the Infringement <>( Patents, and herein the 
contractor is called upon to indemnify the employer againsl any action or loss sus- 
tained owing to any infringement of patent rights. This would be quite satisfactory 
in cases when the scheme was designed by a specialist firm who also executed the 
work a case which is the exception rather than the rule but when the scheme 
is prepared and the drawings supplied by a consulting engineer the contractor can 
hardly be expected to control the question oi infringement of patents, which is rather 
a point for the consulting engineer, who should take the responsibility, and there 
should be no risk of any infringement taking place if the engineer understood that the 

I 2 2 



I 



CONM AUCTION A 1 
KN( INKI K»1N(. — 



FOR REINFORCED CONCRETE WORK 



responsibility was on his shoulders, as it is not necessar) to :i<l<>|>i a patented system 
the rights oi w hu li bel< >ng to anothei party. 

MATERIALS AND WORKMANSHIP. 

In the accord part the materials are dealt with undei the varied sub-headings, 
such as cement, sand, etc. 

Cement. — The cement i- specified to conform in ever) respect with the British 
standard specification for Portland cement, and the contractor is called upon to 
supph ;i signed certificate from the manufacturer with each consignment in show 
compliance with the standard specified. 

Provision i s also made for testing by an independent testing engineer after delivery 
on tin 1 works, and when required tests of the crushing strength are also to he made 
in addition to the neat tensile tests. The cost of the testing is covered by an item 
in the general conditions, which calls upon the contractor to provide an amount based 
upon a certain percentage of the contract sum, this sum to he deducted in full or 
expended as directed ; and this is undoubtedly a satisfactory method. 

The storage of cement is covered by clause 18, which provides that the cement 
may be used direct from the bag if used within 14 days of delivery. If kept longer 
than this period it must he stored in air-tight bins, and in any case the bags must 
be kept in a perfectly waterproof and air-tight shed. 

It will need a great deal of care to see that this clause is rigidly adhered to by the 
contractor, but if this is done it will prove a good clause; as the storage of the cement 
is far too often not considered a sufficiently important matter by those executing the 
w ork. 

Sand. — Three clauses are devoted to the nature and size of the sand to be used, 
and these cover ail the requirements for good work. 

Coarse Material. — This term is used to denote all ingredients of the concrete 
except the cement and sand, this being considered preferable to the word " aggregate," 
which is somewhat uncertain in its meaning, and the clauses relating to this are 
important. The nature, sizes, cleanliness and porosity are dealt with, and very wisely 
a list of materials which are not to be used is given, and by it coal residues and 
slags are prohibited. The materials not permitted are as follows: — 

(a) Coal residues, including clinkers, cinders, ashes, coke breeze, pan breeze, 

slag, or similar material. 

(b) Blast furnace slag, copper siag, forge breeze, dross, and other similar 

materials. 

(c) Sulphate, including plaster of paris and other similar materials. 

((/) Broken bricks containing dust, soot and mortar refuse, or bricks from clay 

containing free lime or pyrites. 
(e) Limestone, magnesian limestone, marbles and other calcium carbonates, 
if the concrete is required to be fire-resisting. 
There are some materials in that list, such as coke breeze, which has been 
used in the past, and often with disastrous results, and we are glad to see 
that they are definitely barred and good work ensured as far as possible. One clause 
deals with the cleanliness of the water to be used in mixing; and the proportions, 
mixing and consistency of the concrete are next dealt with. The proportions given 
are for four different classes of mixture, and they vary from a 1 : 2 : 4 to a 2 : 2 : 4 
mixture, and the cement must be proportioned by weight. 

Mixing. — The method to be adopted when hand-mixing is employed is fully 
described, and the clauses relating to the concrete and mixing appear to fully cover the 
requirements of good class work. 

During the discussion a member suggested that it is preferable to mix the sand 

123 



A STANDARD SPECIFICATION [QQNCKErEl 



and cement together, instead of mixing- the cement, sand and coarse material during 
the first turn, and there is a good deal to recommend his suggestion, which has been 
adopted by a large number of engineers in the past. 

Reinforcement.— The clauses relating to the reinforcement appear to cover all 
the necessary items required in a complete specification, and we are glad to see that 
the adoption of higher carbon steels is allowed for, as there is a great possibility of 
their use, which is advocated by some engineers; and in spite of the controversy which 
exists on the point, and the fact that the Engineering Standards Committee are not 
yet prepared to advise their use, any specification which is put forward as a standard 
at the present time is not complete if it precludes their use. 

The various properties and tests are specified, and all the steel is specified to be 
stored under cover; and anchorage, cleanliness, welding and bends are dealt with. 

Placing of the Reinforcement.— A detailed clause is given under this heading, 
and this is important, as we have seen many instances where the work has been done 
badlv in this respect, not so much on account of negligence possibly, but due to the 
contractor not fully realising that the whole value of a member may be upset by the 
faulty disposition of the reinforcement. 

Provision is made for binding the bars together where necessary, and for keeping 
the reinforcements at the proper distances from the forms. 

Forms. — The clauses relating to the reinforcement are followed by those dealing 
with the forms, and the first of these might, we think, be slightly amended with 
advantage. It is stated that the forms shall be approved by the engineer or architect, 
but the contractor shall be responsible for their sufficiency. It seems rather curious to 
invest the responsible person with the power to approve, while someone else accepts the 
responsibility. It would be preferable to state that the forms shall be inspected by 
the engineer or architect, and strengthened or improved in such manner as he shall 
direct if so required, but such inspection shall not relieve the contractor of his responsi- 
bility as to their sufficiency. We offer this suggestion to the Committee for their 
consideration, as we feel that the clause as at present drawn up does not define the 
positions of the respective parties in a satisfactory manner. 

The remaining clauses dealing with the construction of the forms, their nature 
and removal, are sufficiently complete to cover all the necessary requirements of good 
work, and seem to be well expressed. 

Concreting.— The methods to be adopted in the process of concreting are covered 
by no less than thirty-four clauses, and, although several points of minor importance 
were raised by members during the discussion, these clauses can be considered as satis- 
fa< tory. The placing of the concrete expeditiously, breaks and stoppages, and restarting 
against concrete already hardened, which are important matters, are dealt with in sueh 
a complete maimer that they leave nothing to be desired. Defective work, the protection 
of the concrete, and the suspension during frosty weather, are dealt with, and it is 
specified thai all concreting shall he entirely suspended when the temperature is less 
than 35° Fahr. 

Surface finishes are deall with, and the granite finish for floors, staircases and 
landings is spe< ified in d< tail. 

Piles. - Special clauses are introduced with regard to piles, these relating to the 
removal of the forms, the time of driving, and the lifting or rolling after maturing. 

Fittings, etc. Five clauses are given under this heading, and these deal with 
the question of the fixing and position of pipes and duets, and they are necessarily 
somewhat general in (hara<i<r, as each scheme would require to be dealt with on its 
own merits, and tli<-><- clauses would need to be made more explicit and given in greater 
detail by the Engineer or Architect to suil the proposed scheme. 

Testing.— The last eleven clauses coyer the methods of testing, both for the 
materials and for portions of the completed structure, for the purpose of ascertaining 
i 24. 



1 



ODNXraRTKJNA I . 



FOR REINFORCED CONCRETE WORK. 



the n ushing resistance of concrete it is specified thai the tesl pie< es shall !><• 4 in. or 6 in. 
in cube. Mi". Etchells stated that the Committee had lefl this open, but personally he 
thought i'-in. cubes would give more reliable results, and we agree with him and think it 
would be quite satisfactory to spei if> 6-in. cube as the size • 1 1 1< I eliminate the y\n, cube. 
Mr. S. Bylander, as a representative of the Committee, drew special attention to the 
provisions relating to testing. It was most essential, he said, to define h<>\\ the tests 
w.rc to be carried out and also to find the money for doing them. Il< suggested that 
the percentage of the contract sum to be allowed must var\ according to the size of 
tin- job, but probably 1 to \\ per cent, would be a satisfactory figure. The provision 
for testing covered by this amount would, of course, not include the manufacturer's 
tests, which would be paid for by the contractor direct; and he thought that a clear 
distinction should be drawn in the specification between " Engineer's tests " and 
" manufacturer's tests." 

As to tests of steel, the binding test is undoubtedly the best, and as large-diameter 
bars of high carbon steel are not considered desirable, 1 in. was suggested as the 
maximum. 

Several other members took part in the discussion, and one or two member-, sent 
communications which were dealt with. Mr. R. Colson protested against the use of 
spacers and chairs in between .all longitudinal bars and boarding; and Mr. (i. P. Pimm 
criticised the method described for hand-mixed concrete, and he also dealt with the 
provision for lifting or rolling piles after maturing. The specification provides that 
they must be slung or supported on at least two points one-third of the length from 
each end, and he suggested that it would be better to specify the position of support as 
one-fifth of the length from each end. Mr. T. C. Dawson wondered why coke breeze 
should be barred, as he had seen it used in conjunction with rolled steel joists and after 
thirty years there was not the slightest sign of corrosion. 

Mr. H. J. Harding urged the Committee not to put in conditions which would be 
likely to increase the cost of reinforced concrete, and he also supported Mr. Pimm in 
his criticism of the specified method for hand-mixing. 

Mr. E. P. Wells dealt with the question of hand mixing, and stated that the great 
secret of proper mixing was to have the aggregates moderately dry, to turn the mixture 
three times dry, and not trouble so much about the wet. With regard to the points 
of support in rolling piles, with a 20-ft. pile one need not bother whether the supports 
were one-quarter or one-fifth of the length from each end. With 70-ft. piles four 
supports would be better. After dealing with othet minor matters he expressed the 
opinion that, taken as a whole, the specification was exactly what was wanted. 

Mr. W. H. Lascelles drew attention to the clause which states that the contractor 
is to indemnify the emplcyer against any loss by infringement of patent rights, and 
with which we have dealt in this article. 

Mr. Van Osenbruggcn said he was not satisfied with the specification as it stood. 
He did not consider it necessary to include any conditions of contract in a specification, 
and therefore the whole of Part I. could verv well be omitted. In his opinion many 
of the recommendations went verv much too far. 

Suggestions were also made by Mr. L. C. Hall, Mr. Warden, Mr. G. S. Roberts, 
and Mr. A. Scott. 

Mr. Etchells, in winding up the discussion, stated that most of the points raised 
had already been before the Committee, but nevertheless thev would be reconsidered 
in the light of what had now been said. 

We hope that the final consideration by the Committee will be given at the earliest 
possible moment, and the issue of the specification accomplished at a very early date, 
as the need of such a standard is a very obvious one, and there is no doubt that the 
excellent work of the Committee will be greatly appreciated by all those connected 
with reinforced concrete construction. 

125 



CONCRETE DAM. TEXAS, U.S.A. 



[CONCRETE! 




MAIN CONCRETE DAM AND 

DIVERSION DAM of MEDINA 

VALLEY IRRIGATION 

PROJECT IN TEXAS. 



The accompanying illustrations shoiv the construction -work on the main concrete dam 
and diversion dam of Medina Valley irrigation project in Texas. The great concrete dam 
recently completed near San Antonio, Texas, is 164 ft. high, and contains nearly 300,000 
cu. yds. — ED. 

This irrigation project is based upon the storage of the flood waters of the 
upper Medina River by means of the main dam, which is located at the head 
of the canon through which the stream emerges from a region of rugged lime- 
stone hills on to the rolling coastal plains of south-eastern Texas. 

It may be stated that the lands to be irrigated lie in a solid body of 60,000 
acres in the plain country, at a distance of from 20 to 30 miles from the main 
dam. The lands are of remarkable fertility, are well drained, and have ex- 
ceptional transportation facilities, lying along and between two trunk-line 
railways, the Southern Pacific and the International and Great Northern. 

The water is conducted from the main dam to the lands first in the natural 
river-bed for the four miles of canon, which will be converted into a narrow- 
lake by means of a secondary or diversion dam. This structure is 50 ft. high, 
and turns the water into the canal head. From this point the main canal 
extends 24 miles to the head of the distributing system. 

The cubical content of the main dam is nearly 90 per cent, of that of the 
famous Roosevelt dam near Phoenix, Ariz. The Medina dam is 164 ft. high 
above the river-bed, and from the bottom of the cut-off trench to the top of the 
concrete has a total height of 180 ft. The crest length of the dam is 1,580 ft., 
the base width is 128 ft., and the crest width 25 ft. 

The engineer, Mr. Terrell Bartlett, points out that the foundation is in 
the massive level-bedded limestones, which form the canon walls and all the 
hills of the region. The spillway, 1,200 ft. long, is over a saddle into an 
adjoining ravine. The dam-site i^ about 14 miles by airline from Dunlay, the 
nearest point on the Southern Pacific Railway, and its nearest wagon-haul was 
Originally from I. a Coste, a distance of 23 miles. 

As soon as the bonds for the project were sold, excavation for the founda- 
tion was immediately commenced, and material for camp buildings, machinery 
foundations, etc., was hauled in by a new wagon road from Dunlay. At the 
same time construction was rushed on a standard-gauge railway from Dunlay 
to the dam. 

It is stated lhat on account of the rough character of the country this line 
i> ioJ miles long, with sharp curves and grades of 3 per cent, against 
the traffic, and 3^ rx-r cent, against the returning empties. While this railway 

1 26 



£ 



CtJN.vruiJCTlONAE 



CONCRETE DAM, TEXAS, U.S. A 



w i i s 

si rm 
site. 




in process of construction, the excavation and lighter preliminar) con- 
tion as well as the opening of quarries, were going Forward al the dam- 
and simultaneously all lh< machinery was assembled and heavy timbering 

u as framed al 1 >uniay. 

Id the construction of 
the projecl the railroad w as 
completed the latter part ol 
August, and the plant was 
erected within sixty days 
thereafter, a really remark- 
able performance when the 
unusual magnitude of the 
plant and its isolation arc 
considered. The materials 
for making the concrete 
were all secured at the sin- 
with the exeeption of the 
cement. The quarries are 
in a very hard, chert}-, 
semi - crystalline limestone 
quartz. Sand of a mediocre 
quality could have been ce- 
livered over the railway for 
about $1.40 per cu. yd., 
but it would have been very 
difficult to handle the Urge 
quantity of sand over the 
single-track, steep - grade 
road. 

It is said that the fine 
material and dust from the 
first crushing of the lime- 
stone, together with dust 
from special pulverising 
crushers, were utilised for 
sand throughout ""he dam. 
The cement used came 
principally from the mills 
of three cement companies 
located in the State of 
Texas, making as short a 
haul as possible. 

The mixture of con- 
crete used was 1 cement to 
3J sand (limestone dust and 
fines) to 6J stone. This 
required slightly over one 
127 




c ? 

« a. 

U z 

.5 2 

'J3 H 



b 5 



CONCRETE DAM, TEXAS, U.S.A. ICDNCKETE] 

barrel of cement per cubic yard. Daily tests of cubes and of short, plain 
beams showed a strength of great uniformity. After the dam had reached a 
height above the zones of heaviest pressures it was, therefore, deemed justifi- 
able to decrease the percentage of cement. 

It is held that test specimens with a smaller proportion of cement showed 
a much greater strength than usual in such mass construction, as well as a 
high degree of imperviousness. When this decrease was tried in the dam it 
was found to be detrimental to the plasticity of the concrete and its ease in 
working, and on this account the attempted economy was abandoned and the 
original proportion used for the entire dam. Rubble stones up to 10 tons weight 
were embedded in the concrete. At the bottom from 10 to 15 per cent, of the 
mass consisted of these plums, but toward the top the percentage gradually 
decreased. The percentage for the entire dam was 0/9. 

The contractor's plant was located on the west bluff, which was dictated 
bv the railwav location, which necessarily came in on that side. Adjacent 
to the end of the railway on one side were the storerooms and the commissary, 
and opposite were the shops and lumber yards. A spur track on a trestle was 
carried out over the boiler plant and over the centre of the cement shed, 
enabling unloading of fuel, oil, and cement by gravity. Power was derived 
from seven 150 h.p. boilers, with steam lines to the various engine locations. 
Only the small engine for lighting and the compressors were located at the 
steam plant. 

It must be noted that the two principal quarries were located above the 
dam on the plant side, the farthest at a distance of 2,000 ft. A third quarry- 
exclusively for plums was located in the east bluff below the dam. Skips of 
stone and plums from the main quarries were handled by three standard-gauge 
locomotive cranes on to 4-yd. dump cars. The latter were hauled around a 
loop track to the crushers by four dinkies. 

In this concrete construction work the crushers used were located 
immediately back of the combined mixer bin and screen houses. Bucket con- 
veyors look the crusher run stone to the screens above the stone and sand bins. 
The desired pen cut age of medium sized stone was returned to two disc crushers 
and two hammer pulverisers for making the sand. 

It is pointed out thai under the bins was a mixing deck with five hoppers, 
served by radial cut-off gates from the stone bins and automatic measuring 
chutes for sand. Cement was delivered to tliis deck by a belt conveyor from 
the adjacent shed. On the next deck below was a battery of five I-yd. batch 
mixers, emptying into hoppers. 

On still a third level below was a narrow-gauge track, on which flat cars 
carried the concrete buckets about 75 ft. to the cable-ways. This method of 
deliver}' was used exclusively for the narrow upper portion of the dam. For 
the principal mass of the dam delivery was almost entirely by inclined chutes 
leading from the discharge hoppers down the face of the bluff into a large 
wooden hopper located over the end ol a double-track incline, which extended 

from bluff to bluff, first along the down-stream vdgv. of the dam, and later at 
a high level on the lace of ihc dam. For conveying the material the two 
cableways and control of the Lidgerwood type were used — cables 2 1 in., with 
span of [,050 and 1,270 ft. ; their load capacity was 10 tons. 
12K 



»„<.TONMinJCTIUNAi:i 



CONCRETE DAM, TEXAS, U.S. A 



A car carrying two 2-yd. buckets or 4-yd. pei trip was used on each 
incline track, so that it was possible to send 8 cu. yds. at once to the 
various derricks b) the incline, as well as 2 yds. simultaneousl) by cadi of the 

cables. 

The diversion dam shown in the photograph is also of rubble concrete, 
and is an overflow weir with ogee cresl and railway. It is 50 ft. high, 44 ft, 
wide at ihe base, 440 ft. long, and is arched slightly up-stream. The con- 
struction plant was similar in genera] scheme to that of the main dam, exeepl 
on a much smaller scale, as the diversion dam contains only about one-tenth 




View of Siphon, looking up-stream. 
The Medina Valley Irrigation Project, Texas, U.S.A. 



of the mass of the former structure. An interesting point of difference was 
in the utilisation of fixed guy derricks instead of movable stiff-legs. 

It may be stated that these derricks were placed on pedestals of concrete 
within easy reach of each other, and it was possible to so place the guys as to 
avoid interference with booms or cableways. The lower portion of the pedestals 
became part of the structure, and the upper part was removed upon completion 
of the work. 

The headworks have a double set of metallic gates. The canal is of 
ordinary construction, with about 3,000 ft. of concrete-lined channel in rock- 
cut, the remainder being almost entirely sidehill work in a compact clay. 

Considering the reinforced concrete siphons, it is of interest to note the 
headworks and first mile and a half of the canal are on the west bank of the 

1 29 



CONCRETE DAM. TEXAS, U.S.A 




s s 



■o 5 

.a o 

U X. 
Z 

o 

< 



3> 



c 

H 

w 
x 
H 



130 



. CONMPIKTIONA1 
fv KNCilNl.KWIM'i — 



CONCRETE DAM. TEXAS, U.S. A 



river. The canal is then carried under the river to the easl bank in i reinfoi 
concrete siphon, consisting <>l two bores 8 it. in diameter. After another mile 
the canal is returned to the vvesl bank l>\ means of a similar siphon. 1 wo miles 
of extn meh rough country are thus avoided, and the distance shortened aboul a 
mile. For conveying the water then are in all eleven flumes along the main 
canal aggregating slightly over one mil;' of flume length. These flumes 
consist of creosoted timber trestle of long-leaf Texas pine, with truss and 
towrr construction. The foundations are on concrete pedestals. All timber 
was framed and bored before receiving the 12 lb. creosote treatment. The 
ho -est flume is 95 ft. high and 1,500 ft. Ion-. 





Headgates and Beginning of Canal at Concrete Diversion Dam. 
The Medina Valley Irrigation Project, Te.ws, U.S.A. 

The distribution system is simple and involves no unusual features, except 
the Chacon dam, an earth structure which will collect return seepage waters 
from several thousand acres and storm rainfall from about 70 sp. mi., and will 
also form an equalising reservoir on one of the principal laterals. 

It is claimed that an unusual feature of the project is the enormous 
storag-e of the main reservoir, which has a maximum capacity of 300,000 acre- 
feet. This larg-e storag-e was considered advisable on account of the torrential 
nature of the stream, and it will make possible the conservation of a large per- 
centage of the run-off from the Medina Basin. 



131 



R0H1XTAX X. FRAN MIRZA 



[CONCRETE] 



r= 




*• 



-> ~-^<s 



1 



REINFORCED CONCRETE 

COLUMNS AND THEIR 

CHARACTERISTIC COST 

CURVES. 



^J. 



By ROHINTAN N. FRAM MIRZA, 

B.Eng. (Lvpl.), A.M.Inst.C.E., M.Inst.M.E., Assoc, Royal T.C. 

The following article nvill probably be of interest to those studying the question of 
reinforced concrete costs, — ED. 



IN the present article equations are given to show the variation in the total costs 
of finished reinforced concrete columns, with respect to the amount of reinforce- 
ment employed to increase the resistive power of concrete to compression. The 
author has already treated the same subject with regard to reinforced concrete 
prisms subjected to bending, such as beams, slabs, etc. (vide Concrete and 
Constructional Engineering, Vol. IX, No. 2), and that has led him to further 
investigate the behaviour of costs with varying ratios of steel placed in concrete 
columns. In all phases of engineering it is always of importance to arrange and 
proportion the various elements entering into construction so as to bring about 
the lowest possible sum-total cost. To justify the conclusions it is necessary to 
give some derails of the mathematics used to deduce the same, but several 
intermediate steps are omitted to restrain the length of the article. 

The theory upon which the calculations are based is that set forward by the 
Joint Committee of the Royal Institution of British Architects and many other 
well-known authorities. The nomenclature used is the same as that in the 
Second Report of the Joint Committee of 1911, but with one or two slight 
alterations and additions as shown below : 

m= - = modular ratio, assume tn here =15, and m = m— 1 = 14. 
E c 

#=area of steel in square inches in compression. 

A c — sectional area of concrete in sq. in. in compression, and >4 c = same in sq.ft. 

a 

p= ratio of steel to concrete — —' 

7V total cost. W= imposed load on column in lbs. 

c = the allowable working compressive stressjon concrete in lbs./sq. in. 

t= „ ,, ,, tensile stress in steel in lbs./sq. in. 

a = one side of a rectangular column in feet. 
()<i length of the Other side in feet, hence A' c = 0a\ 
1+0 



6' = 



ve 



S= cos t of steel per cwt. on site of work, including placing, etc. 
132 



I gaWflWCTggB CONCRETE COLUMNS AND THEIR COST. 



Y = cost of centering per sq, yard Oil site of work, including placing, et< 

O ,, ,, concrete per cubic ft. ,, ,, „ „ 

B [1 i m'plc, as will be explained later. 

The money unit for S, Y and Q may be in shillings, dollars, or any other 
unit, but it must be the same for S, V and Q. 

Circular centering and round columns being far less used than square or 

rectangular ones, the latter form will be discussed as the standard example. 

On p. 17 of R.I.B.A. Report No. 2 it is given that \V = c[A c \-{m-\)a\ which 

can be expressed as cA c [\+m'p], and which may be again put in an extremely 

simple form 

W = HlAcB (1) 

B~c 

where B = [l + m'p]c, or again p= — — • 

;;/ c 

The value of c adopted throughout is 600 lbs. per sq. in. 

A c = ~^- and is also = 0a 2 . ' . a= ±\/K 
144B 12 BO 

The following abbreviations are used : — 

R.C. = reinforced concrete. Max. = maximum. Min. = minimum. T c — 

total cost. Sq. = square. 

The total cost of a concrete column of unit height is equal to the cost of 
concrete + cost of steel + cost of centering. The weight of a cub. ft. of steel is 
4"35 cwt., the w r eight of steel used in the column per unit height will be 4'35M C , 
and obviously the cost will be \"55A c pS money units. [The money unit need 
not be particularly in some definite units, but whether it be j£'s, shillings, pence 
or dollars. S, Y and Q must all be considered in the same units.] Hence : — 

T c = A' c O + *t'Z5pAlS + [2* + 2*$]^ (2) 

Substituting values of A' c , p and a in terms of B 

144S 144B m'c 54 B L s $ J 

and differentiating T c with respect to B 

DiT) -WQ( 1 \ , 435 ws .e- vw f _ i \ Y (4) 

a^ain to determine that value of B, which will make T c a max. or a min., it is 
necessary to equate equation (3) to zero and then solve for B, hence it follows 
that 

B =^[Ii^]V^ (5) 

For 6= unity, i.e., when the column is square 

Noting that value of p which makes T c a maximum by suffix c and remem- 
bering that B = [\-\-m'p]c 



r , pis-Q T wo _ -i 



(6) 
>33 



ROHINTAN N. FRAM HIRZA 



[CONCRETE] 



Equation (5) gives all the information necessary to study the effect of varying 
P on T ct but the investigations would not be complete without noting the effect 
of varying W on 7\ : this may best be shown by actually working out two 
examples with some actual data. 

Example I. 125 square (i.e., = unity) columns. W= 14,400 lbs. on each 
column. c = 600 lbs. sq. in. S = 9s./cwt. Q= ls./cub. ft., and Y = 2'7s./sq. yd., 
money units being in shillings. Substituting these values in equation (3), T c 
equation reduces to 

T c =^100(-466- -J- + 4 1 ) (7) 

The total costs corresponding with various values of p (where p= — -, — ) have 

x m c / 

been plotted in Chart No. 1. 

From equation (5) p o = '033 and the chart also shows the same. 

It is important to note that the value of T c at p — is > than that at p = co . 



67- 



6 51 



6_fL 



.&3_ 



$ 



60_K 



J 
59 € 



CHf\RT t 



un -ruxnmbeAi. 



DoJcij_ 

So|AXXrui- co\\vrrvi-v^ 16 feet ^uj^Pu , 12.5 

Q = Onji -oVuiyuna W«^. <UjJ>-«- -foot f<n _ 

C a OOO lbs |pes &cnjLCVu2. i/r\.c£<_ -to com.cAfi-tL i/t\ corn,y»-u.~ •>sj'<?n 

Jo-taX <5oSt = U°St-oJ^co?wTrun. J^€^ ^n-aJt ■^fiA^-Ct J fr 

Load =*V/ * 144 QQ lbs ors l*ch colunn 
Y/&*/n. f=» o«oo Totaju Cost = £& 65-657 
Vlfvcm f = 0*033 & ToUl -&st" u» Plane. amJ. = bb'&SSjz ' 
V^vum. fe OO ToUJl Cos*- is texiot amdL ex^juxSo ,vj^, 4t *^0 



\ 6x \q? q 

SO ^ 



-^oaU. -W w, 14400 Hyo ie &*& ^olttv t^ c/u*Lcai fioouL 

V<* C>v^uc?\.at ckbovJ^ \vuc£o ec^xaJU 58780 \bs) rtcmt*- _ 
3otoJL -^osC ait P = ^><0 /^ Uuj. tfi-ast" |=os;^_bta- volW- . 



5^ 



•i^X %< JT^yii^ny 



5£ 



1 0*2 0-3 



? l-e- RATito OF STE-tU TO CONCRETE 
0-4 0'5 0-6 Q'7 Q«8 0'^ 1»0 H \'5 



>-3 l»4 1-5 >'6 



VI 



EXAMPLE II. In this rase let W = 90,000 lbs. and the other conditions 
remain the same as in Example I. 

p c in this case works out as (,"5X8, as also seen in Chart 2, in which the total 
costs corf ponding to various values of p are plotted, with regard to this example. 

Here it should be noted that T e cit (> — is < than at p co . 

This leads to a very important result, for, given the values of 8, Q and Y 
there must be one value of W which gives T at p = and p = co exactly the 
same and this critical value of W can be obtained by equating the value of 

134 



E 



y„OONM'PlK"T10NAl. 
tV Usj(.lNKKW!N(. — 



CONCRETE COLUMNS AND THEIR COST. 



DC 



W = 



Denoting tins 
(8) 



equation (3) at /> to the value of the same equation at i> 
critical value of W by symbol \\\ 

64xy-> c(l I o? 
9('3KS Of 6 

Solving this for values of S, Q, Y and 0, as given in Examples I and II, 
W c = 38,780 lbs., or about 171 tons, hence 

for values of imposed loading (on one column) lower than that given by W c , the 
I ast possible total cost of that column will be when p=CO {this is possible in 
the case of an all-steel column), and similarly for values of imposed loading 
greater than \\\, the least possible total cost will be obtained when p = 0. 

Curves in Charts 1 and 2 give graphic interpretations of the above statements. 

T~ 




DoJLcx 



I 

T 



ChaKt Sl 



dl 12.3 



. -r\jJ/ri\AK^i_4_ 



SqujOnjL. Gcrtu/m/n_i 16 <&& t-uua?\, am. 

S = O^tuiSuuv-cp \>«a <mA: 4<m. sU-cJL 

Q = OrU2. SrKjuW^l, \-XZ>x. Cm1>-«- -toot l<n CCTvtA*ie- | 



3dtai. "Cost" - CobV6VoTuiO>WrA^rv<M Kxrr^X VuluvVvA >C ' — ^Tq — 5>0 

Load = Vsl = Q 0000 lbs cm. ea.c& <^rWrvq. 



o^ Go-wi-eo^ =. Cs^o^o 

aAtibu.. aJUve y^dJio e^tvJU 36160 \tas")-5W 







3S^P 1U ; .X@P* 



=.Q ajt\&. 



t-e KA"T10 OF STtELTO CQNCRtTE-J - 



o :c \ \*0 



\'2. V*3 1M 



l^Csl 



£ L3-2gS-eyuo^ 



T^,ul.oJt«TJJ.' 



1-6 



Conclusions. — (l.) The total cost of columns having the same resisting 
strength varies with the ratio of reinforcement, and rises to a maximum 
when ratio of reinforcement is equal to the value given by the expression 

- . — I t~^\ Z\2 ~ c k~l+ c > w here S=pnce or steel per cwt., (J — price 

( 16 L Y J (1 + 0)" 

of concrete per cub. ft., Y = cost of centering per yd. All the prices must 

represent the final price after fixing in position, etc., at the site of work, and 

must be in same money units, that is, if S is in shillings, Q and Y must also be 

in shillings. If the column is rectangular is the ratio of one side to the other 

and this ratio is unity for a square column. c is the compressive strength of 

concrete in lbs. per sq. in., and is usually taken as = 600 lbs./sq. in. 

(2.) For values of IV, i.e. imposed loading (on one column) < than that given 

C2 135 



ROHINTAN N. FRAM MIRZA. 



by expression 



64 



y- 



(l + 0) : 



CONCRETE! 

, the T c of that column with nil reinforcement 



9 (-31S-0)- 
is > than the T Ci when p = oo (rising of course to a max. between the extreme 



64 



values of and oc ), similarly when W is > — 



Y 2 



d+oy- 



the total cost 



9 (-31S-Q) 2 

is lowest at p = 0. For square columns and S = 9s./cwt., Q = l s./cwt. and Y = 27 
shillings per sq. yd., this critical value of W is 38,780 lbs. 

(3.) For conditions considered the calculations give true results, but the two 
following facts must not be lost sight of : (a) the superior fireproofing qualities 
of concrete as compared to all-steel columns (which would be the case when p = oo ) 



S^lirrrvo ?~\-kg_&£lA~ \i> ^^KcU/rvCy €>\j\sl£,S-&* , ^ti^ @|£XXmVb ftA.'SvXXVS . ^ 



tik o <S4X»JXWi OL/v^ 




"^Wv^<AlXM>tLo Ouj-vaJ«^) ©^ —^>ati 0-ru2_ "fci "\iLo s «_ Wu C^Vmiv^va 



and again (b) that columns with no reinforcement (which would be the case when 
p = 0) occupy greater space, p stands here for the ratio of steel sectional area to 
that of concrete. 

(4.) For small values of W, the difference between min. and max. T is not 
great, but difference increases rapidly as W reaches higher values. 

(5.) Hooping a column artificially raises the value of c and for calculations c 
will be different to 600 Ibs./sq. in., thus making a corresponding change in the 
deduction of the values of p and W c , when calculating the same for hooped columns. 

(6.) The results are surprisingly different from those obtained by the author 
for Cost Curves of R.C. beams, etc. (vide Concrete and Constructional Engineering, 
Vol. IX., No. 2), in which case the T e curve with respect to p assumes a min. 
value for a certain critical ratio of reinforcement. Such a characteristic curve is 
shown is Chart No. 3. 

136 



J, CONMUlKTIONAlJ 

•v KN(,lNhKWlNt. — , 



CONCRETE COTTAGES IN KENT. 



♦ < 

♦ 

♦ 

♦ 



♦ 
♦ 
♦ 

♦ 

♦ 
♦ 



♦ 













1 !L TV 


TTTrtP^ 


7 


m ■ i 

KP IIUhI 

i ■ ' 






Ml -*■-. ■ jm. «^puf»k 




. * : * " •- . "^^ 


- 



Fig. 1. Some Finished Cottages (back). 



CONCRETE 

COTTAGES 

AT CRAYFORD. 



The following particulars 
ivill doubtless be of interest 
to those concerned in the 
question of rural housing. 
—ED. 



Some very good examples of cottages constructed with concrete blocks are pro- 
vided in the scheme which is now proceeding- for the Cray ford Cottage Society 
in Kent, under the direction of the Rural Housing- Organisation Society, and 
some particulars of the design and construction should prove of interest. 

The estate that is being laid out is a fairly large one, and the scheme 
includes 457 cottages and five sites for public buildings, while portions of the 
land will be given up to a recreation ground, village green, bowling green and 
various allotments, the last-mentioned being in addition to the large gardens 
that are to be provided to each cottage as shown in Fig. 3. 

The site adjoins the River Cray, and is quite close to the village of Cray- 
ford and but a few minutes' walk from the extensive works of Messrs. Vickers ; 
thus it will be convenient to many of the workers in the latter. The concrete 
cottages are being executed by the 
Cottage Construction Co., of 16-17, 
Devonshire Square, E.C., and they 
form the best types of this class of 
work in the vicinity of London, and an 
interesting comparison is afforded 
between concrete blocks and brick- 
work, as regards economy and speed of 
erection in cottage work, which tends 
to show the former to advantage. 

The same type of plan has been 
adopted for the whole of the cottages 
now under construction and com- 
pleted, but the elevations are varied to 
avoid monotony. Each dwelling has 
a frontage of 24 ft. 4J in., and a 
depth of 17 ft. for the main building, 
with a projection of 6 ft. for a length 




rm 



Fig. 2. Cross-Section. 
Concrete Cottages at Crayford, Kent. 



137 



CONCRETE COTTAGES IN KENT. 



w^mB 




'3* 



f ,,ix3N.vn»m-i-ioNAiJ CONCRETE COTTAGES IN KENT, 

f l2 it. al iIk- real oi the ground floor. The accommodation on the ground 
floor consists of a living room 15 ft. 6 in. by 11 ft., a parlour 12 ft. 4) in. by 
<) ft. a scullery, containing hath, a larder, w.c, and fuel store, and on the first 
11 ><>(- three bedrooms are provided, the largesl being 15 ft. 6 in. by 9 ft, and 
the smallest 8 ft. 3 in. by 7 ft. 9 in. Each floor lias a height of 8 ft. in the 
clear and the disposition of the rooms is shown in the plans illustrated in 

FigS. 4 and 5. 




BEDR3DM 2. 



!■ — ■■ — ■■ 



Bedroom 
l*6>$ OL. 




Fi^. 4. First Floor Plan. 



t PAVINfj 






PI 



t_ 6o | u-y ~>n 



#3; 



ScullV 



t«u{ 



h 



Living &3B41 
15 V- n'o" 



m 



if ' J 



Futt 



^ 



n n; 



1 



/ 



*\ 



Paflloi 




■51 



CZ 



^3. 



1SE. 



24-'- 44- 



4 



Fig. 5. Ground Floor Plan. 
Concrete Cottages at Crayford, Kent. 

The contract cost per cottage erected with concrete blocks, without extras, 
works out from ^175 to £179, and it is interesting- to note that the same con- 
tractors' price for the brick cottages was ^15 more than this per cottage. The 
difference in cost amounts to a considerable sum when applied to the whole 
scheme, and there is no doubt that with the methods employed in this instance 
the concrete block construction is superior to the brickwork. The extras refer 
to gables and hipped roofs necessary to secure external variation. The cost of 
these is proportionally moderate. 

139 



CONCRETE COTTAGES IN KENT. 



1CDNCBETEJ 






w 5 



r 1 c 

CJ 

vo w 

ft, « 



U 



I40 



g 



CCN5TBUC 

E^GINhKKlN C- 



CONCRETE COTTAGES IN KENT. 



< 




»+« 



CONCRETE COTTAGES IN KENT. 



[CDNCEEXEJ 



At the present time definite arrangements have been made for 150 concrete 
cottages, and of this number some are completed and occupied, and no less than 
fifty will be completed and ready for occupation in three months from the com- 
mencement of building - . This speaks well for the speed of erection, and will 
not be equalled in the case of the brick cottages which are being erected on the 
same estate. 

The external walls are constructed with a thickness of 9 in., the concrete 
blocks being 9 in. by 9 in. by 16 in., and they are built directly on to the concrete 




Fig. 8. Blocks laid out for Seasoning. 





1 1 . 9. Cottages during Construction. 
Cow RK'u; Cottages at Crayiokd, Kent. 



foundation, which is about 2 ft. wide and <j in. thick. The internal divisions 

are all built will) j / in. breeze, concrete partition slabs made on the same 

machines as the concrete blocks. The whole of the chimney breasts, Hues and 

Stacks are built with the blocks, blocks being moulded lor the Hues, and 



142 



1 



OdNSTIMJCT )UN A I : 



CONCRETE COTTAGES IN KENT. 




Fig. 10. Back Elevation. 
Concrete Cottages at Crayford, Kent. 

different sizes being- employed to give the necessary bond. The gables 
are also finished at the top course with blocks having- one end splayed to suit 
the pitch of the roof, and by this method the " racking- back " is performed 
without the introduction of small filling- pieces, which are generally employed in 
inferior work. The window' and other openings are generally spanned by a 
wood lintel, but relieving arches composed of the blocks are built over same to- 




Fig. 11. A Cottage before Rough-casting. 
Concrete Cottages at Crayford, Kent. 



H3 



■CONCRETE COTTAGES IN KENT. 



IOGNCBETEJ 



take the superimposed load and transmit it direct to the wall on either side 
of the openings. Splayed blocks were used in many cases to avoid sharp angles 
at the sides of openings in the interior of the building, and no trouble has been 
spared in those minor details which affect the character of the finished structure. 
The bedroom floor is constructed with ordinary wood joists boarded on top and 
plastered below, and the ground floor is finished with boarding fixed to splayed 
fillets bedded in the surface concrete. 

The whole of the exterior walls and chimney stacks are rendered with 
cement and sand containing a waterproofing material, and finished with rough- 
cast, thus eliminating any possibility of dampness penetrating the walls, these 
being only 9 in. thick, and not built of blocks moulded with concrete gauged 
±0 give the maximum resistance to percolation of water. It is well known that 




Fig. 12. A Group of Four Cottages. 
Concrete Cottages at Craykord, Kent. 



brickwork 9 in. thick is not sufficiently weather-resisting to keep out the damp 
unless built with a cavity, and the formation of the latter increases the cost, 
and generally causes the whole of the weight from the floors, etc., to be thrown 
on the inner leaf of brickwork, which is only 4A in. thick. The whole of the 
interior walls are plastered with the exception of the scullery, in which the walls 
are finished with distemper applied directly to the concrete blocks, and the 
appearance is very satisfactory. 

Various photographs of the work at different stages and after completion 
are given in the photographic views, and it will be seen that the appearance is 
quite satisfactory from the artistic point of view, although the elevations are 
extremely simple. It will, of course, be obvious that, in cases where the walls 
are finished with rough-cast, as here described, the appearance is the same as 
thai obtained with brick buildings which are treated externally with the same 

144 



\o T C0N5TBUCTI0NAU 
1A EMGTNE.EJHM. ~*4 



CONCRETE COTTAGES IN KENT. 



material, and the concrete block construction is cheaper and undoubtedly 
st ronger. 

The blocks employed in the work are made with a mixture consisting of 
five parts of ballast and one part of Portland cement. The ballast is obtainable 
in the vicinity of the site, and merely requires screening to remove an) large 
stones which will not pass a |-in. mesh, as it is very clean and contains .1 satis- 
factory amount of good sand. The blocks are moulded semi wet and allowed 
to season for a minimum period of fourteen days before being built in the work, 
and they have a much longer period when in position to harden before being 
covered up. No wetting of the blocks has been necessary during- seasoning up 
to the present, as the weather has been excessively wet, and in fact the work has 
been proceeding - during the worst possible weather conditions, and this is an 
important factor when the great speed is considered. 

The blocks have also required to be protected during- the frosts, and in 
spite of adverse conditions they are very sound and strong-. It is roughly 
estimated that 80,000 blocks were required for the first fifty cottages, and the 
whole of these have been made on the site with four machines supplied by 
Winget, Limited, 25, Victoria Street, Westminster, S.W., and Newcastle-on- 
ly ne, the type of machine being so well known as to need no special description. 




HS 



CONCRETE ROAD CONSTRUCTION. 



[CONCRETE] 




CONCRETE ROAD 
CONSTRUCTION. 



The following notes on Concrete Highiuay Construction have been prepared for us by 
Mr. A. N. Johnson, the State Highway Engineer of Illinois, U.S.A. — ED. 



GENERALLY. 

The use of water-bound macadam and gravel roads has been very common 
throughout the United States, and for a number of years served ail needs of 
traffic, but with the increase in the number of motor vehicles using the roads 
the cost of maintenance increased very rapidly. This led engineers to try other 
forms of construction which would be more durable under motor traffic. 

In the States where the soil is a heavy black loam, common to the so-called 
Corn Belt, the waterbound roads also suffered considerable damage from the 
sticky mud which was carried on to the surface of the road by traffic. At 
certain times of the year the consistency of this mud is such as to render it very 
sticky, with the result that it would adhere to the wheels of the vehicles and also 
to the stones in the road, pulling them out and making the surface rough and 
uneven. 

In order to prevent the damage done by this mud and by motor traffic to 
waterbound roads, many engineers have resorted to> the use of a bituminous 
binder for the surface of the crushed stone roads. 

Under some conditions this construction seems to be very satisfactory, 
but in the Corn Belt it is found that the bituminous binder is more or less 
injured by t he sticky mud which is carried on to the road surface, so that while 
this form of construction is satisfactory so far as motor traffic is concerned, 
it does not entirely prevent damage by mud. 

These conditions have led engineers to try other forms of construction, and 
among those that have been developed is the concrete road. 

THE CONCRETE ROAD. 

In the work of the Illinois Highway Commission, the concrete roads have 
been built of widths varying from 12 ft. to iS ft. The 12 ft. and if) ft. roads 
have been made 6 in. thick, while the wider roads have been made S in. thick 
at the middle rind 6 in. thick- at the edge. The surface is constructed with a 
cross slope of | in. to the foot. In order to prevent dislodgment of the slab 
of concrete by the freezing of water which might run in under it, underdrainage 
is provided. 

Drainage. — The underdrainage consists of longitudinal trenches about S in. 
wide and 6 in. deep, constructed along each a\^;c of the pavement, the trench 
being filled with broken stone. In addition to the longitudinal broken stone 

146 



tf, ODNM LUKTIONA1. 
*V KTM(.INH-.P1NC. — „ 



CONCRETE ROM) CONSTRUCTION 



drains, cross drains arc constructed every s () ft., running from the longitudinal 
drains t<> the gutters. These cross drains are also filled with broken stone to 

within lour 01 five inches <>i tl"' surface <>l the side load, and then covered with 

earth. 

[ggre gates. The aggregate for the concrete may be either broken stone 
and sand or properly graded natural gravel, and it is believed thai the gravel is 

much superior to the broken limestone, since the particles of gravel are hard 
and will wear much longer than the broken limestone. II trap rock or granite, 
<>r equally tough rocks are available for the aggregate, they are satisfactory. 

It is important that tin- particles of coarse aggregate near the road surface 
shall be' completely surrounded with cement mortar, so that there will be no 
possibility of dislodgment of the farger stones under traffic. If individual stones 
are dislodged from the surface, a break is started which will increase gradually 




Concrete Road Construction in U.S.A. 

under traffic, until it becomes of a size requiring- repairs, if the road is to be 
preserved. For that reason the mixture of the concrete should be such as to 
provide an excess of mortar, and consequently the mixture of one part cement, 
two parts of sand, and three and one-half parts of gravel pebbles or broken 
stone is used. The surface of the road should be somewhat granular, so as 
to afford a good footing- for horses, and should, therefore, be finished with a 
w r ood float which should be used merely to flush sufficient mortar to the surface 
to surround thoroughly the larger pebbles in the aggregate. 

Precautions against variation in temperature. — In order to take care of the 
change in length of the concrete pavement under variations in temperature, 
expansion joints are provided every 50 ft., and it has been noted that the 
weakest place in the concrete surface is at the expansion joints. The steel tired 
wheels rolling across the joint have a tendency to break down the concrete, and 

1+7 



CONCRETE ROAD CONSTRUCTION. 



(ogNoa Erai 



unless protected from this sort of damage, the pavement deteriorates rather 
rapidly at the joints. Several methods are being- employed to prevent this 
damage. One plan is to use a pair of steel plates, one being attached to each 
of the slabs which come together at the joint. The plates are separated about 
one-half inch when the road is constructed, and the opening filled with some 
compressible material, such as asphalt. 

Another method is to use a row of creosoted wood paving blocks at the 
joint. 

General Construction. — In constructing the roads the following general 
method is being used by the Illinois Highway Commission. The road-bed 
throughout a considerable portion of the length of the road is shaped and rolled, 
and the aggregate dumped on this prepared road bed in approximately the 
quantities necessary for the concrete. The mixer used is one which takes 




>*vV 



"J/* '?•'•'" r^t f; 



Concrete Road Construction in U.S.A. 



the material in at the front end and delivers it at the rear. The mixing drum is 
loaded by means of a chute which is let down on the ground for filling, and is 
then raised until the aggregate is dumped into the drum. The concrete is 
distributed on the roadway by means of a bucket which travels along a boom 
at the rear of the machine, and can be automatically dumped at any place 
desired. The boom is adjustable as to height and can be swung in a circle 
across the roadway. The machine is mounted on wheels and moved along the 
rf>ad under its own power. The various processes in the construction are best 
^liown by the accompanying photographs. 

ROAD BRIDGES. 

In considering the development of any considerable mileage of American 
highways, the bridging of waterways must be given careful consideration. 

In the State of Illinois practically all of the bridges and culverts built prior 
148 



^CONSTIHRTIONAI. 
*.F.lMC.lNht-.KUSt. — 



CONCRETE ROAD CONSTRUCTION, 



to [907 are either temporal") wood structures or light steel structures provided 
with \\(M)d doors. It has been found that on account <>f the excessive and 
constantly increasing cost <»i maintenance, it is highly importanl that permanent 
bridces be built, wherever such structures arc economically possible. 

Reinforced oncrete slabs for openings, varying in width from a feu feet up 
to 2^ or >° ''•< are particularly adaptable to country highwa) conditions. The 
principles of construction arc simple enough, so that it is not difficult to find 

men competent to build them, whereas, in arch Structures and the more COfll- 

plicated forms of beam and girder construction, the principles of design are 
more or less involved and require care in construction not easily obtained. 

Comparing simple slab designs with beam and girder designs, the econo- 
mical limit of span length as regards materials is considerably under 30 ft. 
for simple slabs, but owing- to the increased difficulty of securing workmen 
competent to build the more complicated designs, there is but little saving in 
using- the beam and girder design for spans shorter than thirty ft., unless con- 
crete materials at the bridge site are exceptionally costly. On the other hand, 
where concrete materials are exceptionally cheap, simple slabs can be used to 
advantage for longer spans. Simple slabs have been economically used for 
highway bridges having clear spans of 42 ft. 

For longer spans reinforced concrete " deck " or " through " girder bridges 
may economically be built with clean span lengths of 60 or 70 ft. In 
deigning such bridges it is equally important from considerations of economy 
and good workmanship to make the design as simple as possible. 

As the span length or the cost of materials on the ground increases, it 
becomes more and more important to avoid the use of surplus material. It is 
rarely advisable or economical, however, for the ordinary country highway 
bridge to make the design complicated, such, for instance, as results from the 
use of floor beam and slab construction, for the floor system. 

It is true that by lightening the floor system, as much as possible, by using 
floor beams, longer girder spans are theoretically possible, but the conditions at 
the bridge site are ordinarily such as to make it more economical to use two 
or more shorter spans rather than one long one. For instance, a 70 ft. rein- 
forced concrete superstructure with a 16 ft. roadway would cost, under average 
conditions, about $2,600.00. Under the same conditions, two 35 ft. reinforced 
concrete girder superstructures would cost about $1,500.00. The two span 
bridge would, therefore, be cheaper, provided the pier could be built for less 
than $1,100.00, which would usually be the case. 

Arch Construction. — Under proper conditions the arch may well be used 
in place of slabs or girders. Where rock or other foundation of unchangeable 
character may be obtained within a reasonable distance below stream bed, and 
where there is plenty of head room and the span is long, the arch may prove 
to be the economical design to use. 

Slabs or girders are better adapted, however, to conditions of ordinary 
head room and for foundations requiring piles, or which may permit settlement 
of the abutments. 

The advantages of the slab or girder design over the arch are due chieflv 
d 1+9 



CONCRETE ROAD CONSTRUCTION. 



rCQ NCBETB 



to 'the following facts : The pressure on the foundation is vertical and no 
precaution need to be taken to avoid sliding. The weight of the structure 
complete is much less, requiring- less costly foundations. With the superstruc- 
ture separated from the substructure, no damage whatever occurs from a con- 
siderable settlement of either or both of the abutments, whereas the settlement 
of one of the abutments of an arch structure would produce unsightly crarks 
and dangerous stresses. 

Expansion rockers can easily be provided so that there are no temperature 
stresses in the superstructure. The effect of chang-es of temperature is too 
often neglected in arch design. Lastly, the area of waterway may be greater 
for the same length of span. 




Concrete Road Construction. 



KO 



/, 1&N.V1TJIK' JION h I 
\ | NdlNt.lK'INt. — . 



MODERN METHODS (>!•' ARCH CALCULATION. 




RECENT VIEWS ON 
CONCRETE & REIN^ 
FORCED CONCRETE. 



Recent Papers & Discussions. 



// is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method tve are adopting, of dividing the subjects into sections, is, ive believe, a 
neiv departure. —ED. 

THE CONCRETE INSTITUTE. 

SOME MODERN METHODS OF ARCH CALCULATION. 

By EWART S. ANDREWS, B.Sc, M.C.I. 

The following is a short abstract of a Paper read at the $$th Ordinary General Meeting 
of the Institute. 

The arch is a form of structure which possess* - great advantages from the standpoints 
of beauty and economy, and from the earliest times the arch has been used in all kinds 
of constructional work. In the present paper arches are not considered at all from the 
point of view of architectural styles or orders, but consideration is restricted to the 
calculation of the stresses in them. 

The arch presents points of considerable difficulty from this point of view, and the 
resulting formulae are elaborate. Some may contend that the formulas are too elaborate, 
and that " simple practical rules " are just as good ; one answer to such contention is 
that such simple rules would be welcomed if they really were as good. The difficulty 
is that, unless simple rules are applicable over a wide range, and have been fully tested 
by scientific experiment, there is considerable danger in their use. 

There is, unfortunately, among some practical engineers a strong antipathy to 
complicated formulae — an antipathy which is usually stronger in proportion as the 
formulae are not understood — but closer acquaintance with such formulae and some 
useful spadework in the form of the compilation of tables and diagrams, usually helps 
to dispel much of the dread. The primary reason of the difficulty in the determination 
of the stresses in arches arises from the fact that, in most cases, the arch is what is 
called " a statically indeterminate structure," so that the forces acting upon the arch 
cannot be found by the ordinary laws of statics. Exactly similar difficulties arise in 
the case of stiffened suspension bridges, continuous beams, and slabs. 

The stresses in an arch can be found as soon as we can find the magnitude and 
position of the reactions; these reactions (R) may be considered as compounded of 
vertical components (T") and horizontal thrusts (H) ; if, as is usual, all the loads on 
the arch are vertical, the horizontal thrust (II) must be the same at each end. 

We can then draw the line of pressure, linear arch, or equilibrium polygon (three 
alternative names for the same thing) for the given load system upon the arch. 

Then, by Eddy's theorem that " the bending moment at any point of an arch is 
equal to the product of the horizontal thrust into the vertical intercept bvtween the 
centre line of the arch and the line of pressure,' 1 we have — 

Bending moment at any point = P=7/ 8 
If the line of pressure comes below the centre line of the arch, the upper surface or 
extrados of the arch will tend to become in tension ; and if the line of pressure is above 
the centre line of the arch, the lower surface of intrados of the arch tends to become 
in tension. 



D2 



I ;i 



THE CONCRETE INSTITUTE. [CONCRETE] 

Stresses in tlic Arch. — -To obtain the stresses in the arch we first find the thrust 
or normal pressure (O) and the shearing force (5) at the point by resolving the thrust 
(() ) at the point under consideration along and perpendicular to the centre line of the 
arch at the given point. 

Then, if A is the area of the section, and M c , M t the compression and tension 
moduli, we have — 

Maximum tension stress = t = ~rr~ ¥ (1) 

M t A 

xi ■ H8 O , . 

Maximum compression stress = c= — \l) 

M c A 

Mean shear stress = s= - (3) 

There is therefore no difficulty whatever in the calculation of stresses in arches 
when once we know the horizontal thrust. 

Cases in which the horizontal thrust can be found without the elastic theory of 
arches : .these are .as follows : — 

i. Parabolic arch uniformly loaded over whole span- — 

8v 
w=laa<d per unit length, 
I = span of a rch , 
x; = rise of arch. 

2. Parabolic arch with uniform load extending from an abutment to the centre — 

H= wV 

3. Arch of any shape provided with hinges. In this case the line of pressure can 
be drawn by the well-known graphical construction for making a link-polygon pass 
through any three given points ; then the polar distance of the vector diagram gives 
the horizontal thrust desired. 

This theory, to which the author's principal attention was given, is based upon a 
consideration of the deformations which an arch-rib obeying the ordinary laws of 
bending will receive. From these deformations we are able to calculate the horizontal 
thrusts. 

Let 5s represent a very short length between two points of an arch-rib, one end 
of which is considered as fixed relatively to the other end, and suppose that the bending 
moment along this very short length is B. 

If E is the elastic (Young's) modulus and / the moment of inertia of the rib, it 
can be shown by the theory of beams that — 

A y = vertical displacement of the end due to bending 

= y? ?g! (i) 

A x = horizontal displacement of the end due to bending 



2 



Byls {2) 



A El 



A @ = angular change of tangent to rib at end 
\D 



2 



*** (3) 

A hl 



These are the general] formulae upon which all thr special formulae are based, and 
it should be noted in passing that they are the deformations <hw to bending only and 
do not include those (\u<- to direct thrust ; we will refer to the effect of the latter at 
a later stage. 

152 



/rgwsraycTwuLi MODERN METHODS OF ARCH CALCU LATlOX . 



K^QiNKKWINC. -^, 



I li< s< genera] Formulae \\<i<- then applied to the mos( common special cases "I 
i igid arches, \ i/. : — 

(i) Arches with two hinges 01 pin joints, i.e., two-pinned arohes. 

(2) Arches without hinges, i.e., !i\<<l arches. 

In a Paper of ihi> kind ii was manifestly impossible to <1< ;il fully with ;i subjecl 
upon which several long text-books have been written, and ii might very well be thai 
many Importanl points have been omitted. The author hoped, however, thai a study 
of the Paper would enable those who had nol had the opportunity of a complete stud) 
of th< arch theory in its more general suspects to follow the fundamental relations upon 
which scientific calculations were based, and that their interest would b<- sufficient h 
aroused to encourage them to study the subjecl more fully. 



THE SOCIETY OF ARCHITECTS. 

THE CONSTRUCTION AND PROTECTION OF 
BUILDINGS IN RELATION TO FIRE. 

By A. ALBAN H. SCOTT, Vice-President. 

At a meeting of tJie Society of Architects held last month an interesting Paper 
was read by Mr. Alban Scott on the Construction and Protection of Buildings 
against Fire. We give below an abstract as far as the Paper dealt with con- 
structional matters. The latter portion, not reproduced here, dealt mainly 
with equipment and tire extinction. 

Introductory.— With all the means at our disposal to-day for preventing and 
fighting fires we still have appalling loss of life and damage to property through fire. 
Every year improvements are made in all branches to prevent such loss, and again 
every year seems to bring forward also more hazardous trades, more concentration and 
other causes of large loss. 

In giving a paper of this description it would be impossible to do so without 
referring to that excellent institution, the British Fire Prevention Committee, with 
which two of our members, namely, Mr. Edwin O. Sachs and Mr. Ellis Marsland, have 
been so long associated, and have taken such an infinite amount of care and devoted so 
much time to its work. Although I have been a member of the British Fire Prevention 
Committee for some period and duly receive from time to time their valuable publica- 
tions, it is only when one commences to study them in detail that one fully realises tne 
enormous ground such a Committee cover; from the testing of flannelette up to the 
testing of heavy reinforced concrete floors, and special commissions and reports on 
what our friends in France and Russia have done in fire precautions. 

London Building Acts. — In reading through the London Building Acts with fire 
precautions specially in mind, it is pleasing to note what great care has been taken 
generally regarding the construction of buildings from the fire point of view. In spite 
of all these precautions, I think additional provision for escape of occupants in case of 
fire should be provided and the powers given to the Council still further increased in 
this respect. 

It would be advisable for the London Building Acts, and in fact all our by-laws 
throughout the country, to make it compulsory that all external walls and internal 
partitions and floors are constructed of fire-resisting material. This sounds perhaps 
rather a startling proposition, but if we just consider for a moment the following 
figures, it does not perhaps mean quite such a drastic expense as one would think from 
an outline statement. 

The whole of the following costs have been based on the current cost of materials. 

Floors. Wooden floors suitable for domestic buildings taken in 
spans of 12 ft. ... 

Fire-resisting floor, ditto ... 

Wooden floors for workshop at 200 lbs. super load per square foot. 
Spans 10 ft. 

Ditto, ditto. Fire-resi>ting floors 

(Basis of last two items taken for floor 30 ft. by 100 ft.) 

153 



r ft. sup 
Prnce. 


H'3 


1 7 '3 


28-9 


34*4 



THE SOCIETY OF ARCHITECTS. [CQNCBET E 



Per yd. sup. 
Pence. 
('(>>; in wood framed partition, plastered on both sides, per yard 
suj ei ... ... ... ... ... ... ... ... ... ... 7 2 '8 

Cost of fire- resisting partition, plastered on both sides ... ... 72*0 

It would, I think, be a great mercy to the building owner, the community generally, 
and to architects if the London Building Acts were in force through the country (with 
certain modifications), and administered by district surveyors of the same standard and 
training as in London. 

I do not propose 10 touch upon all the points in these Acts which relate directly or 
indirectly to lire prevention in its various aspects. The widths of streets and frontage 
lines indirectly bear upon the point as well as courts within a building and space at 
nar of domestic buildings. As to the courts, I would like to see introduced that where 
the opposite walls of courts are less than a certain distance apart all openings in 
the walls should be protected by fire-resisting wired glass and hard metal frames and 
sashes. 

Clause 62 should be so amended that all floors, irrespective of height, should be 
constructed of fire-resisting material. 

Clause 64. The word " stone " should be deleted and corbels for all chimneys 
should be supported on fire-resisting material other than stone or hard timber. 

As indicated elsewhere, I suggest Clause 68 should read that all floors and 
staircases, irrespective of the size or use of the building, should be constructed of fire- 
resisting material, and further the top floor constructed of such strength that if the roof 
is not also constructed of fire-resisting material it would successfully withstand the 
collapse of the roof in case of fire. 

Many fires have become a total loss owing to the roof or one floor collapsing and 
causing the whole series of floors to collapse like a pack of cards unsupported. 

Clause 74, Sub-sections 2 and 3, should be amended similar to the suggestion for 
Clause 68. 

Clause 80 with but slight qualifications should be made applicable to existing 
buildings as well as to new buildings. 

In the London Building Acts (Amendment) Act, 1905, we have a revised list of 
materials to be deemed fire-resisting, as follows : — 

(I). For general purposes : — 

1. brickwork constructed of good bricks, well burnt, hard and sound, properly bonded, 
and solidly put together. 

(a) With good mortar compounded of good lime and sharp clean sand, hard clean 
broken brick, broken flint, grit or slag, or 

(b) With good cement, or 

(c) W"\\\\ cement mixed with sharp clean sand, hard clean broken brick, broken 
flint, grit or slag. 

1. Granite and other stone suitable for building purposes by reason of its stability 
and durability. 

3. Iron, steel and copper. 

4 Slate, tiles, brick and terra-cotta when used for coverings or corbels. 

--. Flagstones when used for floors over arches, but such flagstones not to be exposed 
on the under side, and not supported at the ends only. 

6. Concrete composed of broken brick, tile stone chippings, ballast, pumice or coke 
breeze and lime cement or calcined gypsum. 

nbinal ion 1 < oncrete and steel or i ron. 
(II). For special purposes : — 

1. In die case of doors and shutters and their frames, oak, teak, jarrah, karri, or 
odier hard timber not less than \'\ in. finished thickness, the frames being bedded solid 
to tie- .vails or part n ions. 

2. In tie- case ol staircases and landings, oak, leak, jarrah, karri, or oilier hard 
timber. The treads, irings, risers and hearers being not less than 1 ;J in. finished thick 

ness, and the ceilings and soffits, H any, being of plaster or cement. 

3. Oak, teak, pirr.ih, karri, and other hard timber when used bo- beams, posts, or in 
combination with iron, the timber and the iron (if any) being protected by plastering ui 
oth-i incombustible or non conducting external coaling not less than 2 in. in thickness, 
fir in th -.I limber not less than 1 in. in thickness on iron lathing. 

4. (a) In tie 1 .1-' 1 floors .ind roofs. 
154 



N>T1.HJCT10NAL1 
"A EN GINEERING — -J 



PROTECTION OF IWlLhIXCS AGAINST FIRE. 



Brick, iilf. terra-cottu ci concreti compoi 1 1 a di cribed in paragraph I . (6) <> I 
i Ins schedule, not less than 5 in. thick in combination with iron 01 steel. 
(/o In the case ol floors and of the roofs "l projecting shops. 
Pugging <>i concrete composed as described in the said paragraph I. (6), no 
ill. id 5 in. thick between wood joists, provided .1 fillel 1 in. square is secured to th<- 
sides of the joists, and placed so as to be in a central position in the depth of the 
concrete, or concrete blocks no( less than 5 in. thick, laid between wood jois 
fire- resisting bearers secured to the sides of joists. 

5 In ilic case of verandahs, balustrades, and outside Landings, the treads, -ii-in^- 
.ml risers of outside stairs, outside steps, porticoes and porches, oak, teak, iarrah and 
karri, or other hard timber, no! less than 14 in. finished thickness. 

(>. In the cist' of interna] partitions, enclosing staircases and passages, terra cotta, 
brickwork, concrete or other incombustible material nol less than 3 in. thick. 

7. In the case of glazing for windows, doors, borrowed Lights, I. intern or skylights, 
glass not les> than 4 in. in thickness, in direct combination with metal, the melting point 
of which is noi Lower than i,8oo degrees l-'ahr., in squares not exceeding i<> square inches, 
and in panels not exceeding 2 it. across either way, the panels to be secured with fire 
resisting material in fire-resisting frames of hard wood, not less than 14 in. finished 
thickness or of iron. 

(111). Any other material from time to time approved by the Council as fire- 
resisting. 

In Section 1, Sub-section 2 of this list, we have "stone suitable for building by 
reason of its solidity and durability." 

Certain stone which meets the requirements of this clause are quite unsuitable 
for lire-resistance, and might come under the heading of incombustible material but 
not fire-resisting. 

Slates under Clause 1, Sub-section 4, should be omitted for corbels. Slates will not 
successfully stand heat and water. 

In Clause I., Sub-section 6, concrete formed of coke breeze is permitted, but 
should be prohibited where it would come in contact with steel, and should not be 
taken as applicable to I., 7. 

In II., 3, plaster protection is allowed to be 1 in. in thickness on timber in lieu 
of 2 in., if metal lathing is used. From certain fires, it would .appear that the metal 
lathing was of very little help in retarding fire. 

In II., 4 (a), concrete requires to be not less than 5 in. in thickness. 'Ibis I 
suggest for roofs could be safely reduced to 3-5 in. and to 4 in. for floors. 

In II., 4 (fe), pugging, which is generally very indifferently executed, should be 
omitted from fire-resisting materials. 

Clause 7 of the 1905 Amendment Act I should like to see amended to read that the 
Council is to be satisfied as to means of escape in case of fire to all buildings irrespective 
of whether they are " high buildings " (that is upper storey greater height than 50 ft.), 
or provide sleeping or working accommodation for more than twenty people. 

(In the case of workshops employing 20 or less I believe one of the Government 
Departments look after.) 

Insurance Companies' Requirements. — It might be of interest to slightly touch 
on the insurance companies' requirements. 
Standard ib. 

Vs to fire-resisting construction they have various 
standards : — 

Such as Standard iA, Standard iR. Standard 2, 
Standard 3. 

The Standard iA deils with cotton flax, woollen 
and worsted mills. 

The Standard ib requires that buildings be not 
more than 80 ft. in height and cubic contents of any 
one compartment not to exceed 60,000 cubic ft. 

Walls to be of brick, terra-cotta, or concrete, and 
not less than 13 in. thick, but if plain concrete not 
Less than 20 in. 

Partitions to be of incombustible material, except- 



Standard 2. 



13 i : to, but not less 
than 13 in. thick. 



Di'to, but parti 



Standard 3. 



Ditto, but not 
less than q in. thick. 



i 3 



THE SOCIETY OF ARCHITECTS 



Standard ib. 

ing only office enclosures, which are to be of hard 
non-resinous wood. 



All flues to have brickwork not less than o in. 
thick towards 'he interior, and no woodwork to rest 
in or be plugged into the brickwork of any flue. 

Openings in external walls not to exceed half the 
area of any storey. 

All window frames and sashes to be ot iron or 
other hard metal, and all windows above ground 
floor to be glazed with glass not less than i in. thick 
in sections not larger than 2 ft. sup., and all open- 
ings above the ground floor opposite, and within 

20 ft. of any window or other glazed opening, and 
within 20 ft. of any roof to be protected by " Fire- 
proof " shutters or doors. 

Floors to be brick arches, terra-cotta, fire-clay, or 
concrete not less than 6 in. thick. 

Wooden flooring permitted if laid close to floor 
with no space. 

Solid wood floors, not les-s than g in. thick if 
ceiled with plaster and covered with floor boaras 
(no space), are also allowed provided waterproof 
lining is provided underneath the floor boards. 

Scuppers to carry off water to be provided of 

21 square inches every 12 ft. apart on each floor 
(buildings in C. of L. or L.C.C. scuppers not essen- 
tial). 

Roofs to be entirely of incombustible materials 
as for floors, but not less than 4 in. thick. 

Glass not less than \ in. thick, in sections, not 
exceeding 36 square inches, set in hard metal and 
wired glass and electro copper glazing considered 
as incombustible 



IQONCPXlE) 



Structural Metalwork. All columns and stan 
chions to be covered with brickwork or porous 1err:i 
cotta 2 in. thick, or concrete or plaster ii in. thick, 
keyed into mct;il supports and protected for a 
height of 4 It. from floor where cement concrete or 
p'aster only used. 

All other metal work, including roof work, to be 
encased in porous terra-cotta 2 in. thick, securely 
anchored, or cemenl concrete or plaster r in. thick, 
keyed into metal supports. Provision to be made 
in ;ill c;is< s for expansion. 

.56 



Standard 2. 

tions of metal lath- 
ing and plaster on 
wood f 1 a m e 
allowed. 

Ditto, but if ren- 
dered with i-in. 
cement brickwork 
may be 4^ in. 

Ditto. 

Ditto, but in lieu 
of " fireproof " 
shutters wired glass 
may be used sub- 
ject to certain con- 
ditions. 



Ditto. 
Ditto. 
Ditto. 



Roofs to be en- 
tirely of incombus- 
tible material, glass 
allowed in roof if 
not less than i in. 
thick not exceeding 
5 ft. sui)., or wirea 
glass or electro 
copper glazing, in 
each case set in 
hard metal outlets 
to meet require- 
ments of Factory 
and Workshop Acts 
allowed subject to 
certain conditions. 



All Colli 

stanchions, gi 
joists, lintels 

other metal 
[excluding I' 

work ol roo I 

be c.isc (| 2 in. 

or with 1 in. 
crete or pfiist 
Standard ii«. 



in n s, 
rders 

and 

work 

rainc 

's) to 

thick 

con 

it as 



Standard 3. 



Ditto, but 3 in. 
thick. 
Ditto. 

Ditto, but 6 in. 
thick, and all sup- 
ports and stanchions 
and other structural 
metal work covered 
widi plaster or con- 
crete, etc., I in. 
thick. 

Having no com- 
bustible material in 
its construction. 
Flat roots of simi- 
lar construction to 
solid wood floors, 
but 4 in. thick. No 
floor boards, but on 
upper side covered 
with metal, con- 
crete, asphalt, or a 
composition of as- 
bestos and other 
incombustible 
mineral ingredients 
or vulcanite having 
a coating of at least 
2 in of sand or 
gravel. 



Sec previous note. 






j r dONMUWCTIONAl. 
f^ ENGINEERING — . 



PROTECTION OF BUILDINGS AGAINST FIRE, 



STANDARD iH. 

K< mm' \\i> ( 'hi INGS. 

\.. lining <>i wood or textile fabric allowed to 
any pari of walls, partitions, ceilings <u roof. 



Fl OCR ( li'KMMiS. 

Only holes for driving shafts, iron or earthenware 
tubes for e'ectric conductors, and these to be 

specially dealt with. 

Staircases practically as required lor emergencj 
exits by L.C.C. Where staircases and hoists extend 
to top floor, enclosure must be roofed with glass 
roof protected (subject to certain restrictions in 
L.C.C. area I. 



All belting and rope races to be enclosed as for 
staircases and hoists. 

Shafting through walls to fit closely into wall, 
and to have closed wall boxes leaving no open space. 



Pipes, eU. Xo wooden casing allowed. All 
pipes (except water pipes not exceeding i^ in. 
diameter) to be of hard metal. 



Communicating Compartments. 

Two or more compartments (constructed according 
to the rules) may communicate provided their aggre- 
gate cubical contents do not exceed 60,000 cubic feet. 
vYhen cubic contents exceed 60,000 cubic feet com- 
munication only allowed across a fireproof com- 
partment, built up from the basement with walls of 
solid brickwork, and having all openings protected 
by fireproof doors at least 6 ft. apart. 

Reinforced Concrete. 

Reinforced concrete buildings allowed subject to 
the usual precautions. 

The requirements as to proportion of cement m 
the concrete are somewdiat ambiguous, viz. : — 

" In the proportion of six cwts. of cement to each 
cubic yard of concrete." 

All external walls to be not less than 6 in. thick. 



Si ANDARTl 2. 

I )itto, ex 1 ep I 
dado allowed in 
wood noi exceeding 

6 ft. hi^h in olli< es, 
cellars, stain ases 
and passages pro 
vided not used lor 

storage. 



Ditto 



Ditto. 



Ditto. 
Ditto. 



Ditto. 



Ditto 

Ditto. 
Ditto. 



7DARD \ 



Ditto. 



lie ; -ts to be en 
1 Losed in walls r > in. 
concrete or R.< '. 
3 in. 'hick with ' 
resisting doors. 

Sprout or 

trunks not exceed- 
in. square 
area con- 
of iron 
thick and 
to every 



ing 4 
feet in 
structed 
rV, in. 
shutters 
opening. 



Openings up to 
12 square feet with 
double iron or 
metal covered trap 
doors (special con- 
struction). 

Staircases having 
steps and landings 
of brick, stone, 
iron, concrete en- 
closed with walls, 
this applying also 
to vent shafts, all 
openings being pro- 
tected. 



Ditto. 



Ditto. 



Between piers 
5 in., ditto. 



157 



THE SOCIETY OF ARCHITECTS. 



RENeK ETEl 



Ditto, 

thick. 
Ditto. 
Ditto. 



Ditto. 
Ditto. 



Standard 1b. Standard 2. Standard 3. 

Division walls 8 in. thick. 

Partj walls 13 in. thick except if adjoining reii 
forced concrete building, then S in. thick. 

Floors 4 in. thick if lined with fire tiles i£ in. Ditto. 
thick. 

Floors 5 in. thick and supported on beams and Ditto. Ditto, but 3 

columns of reinforced concrete. 

Roofs 3 in. thick Ditto. 

Xo metal to be nearer face than double its dia- Ditto, 
meter, but not less than 1 in. and need not exceed 
2 in. 

Enclosures and staircase and hoists 6 in. thick. 

Fire-resisting compartments to have walls 8 in. 
end floors 5 in. thick. 

Under Standard IV., the party and external walls to be not less than 9 in. thick of 
brickwork, etc., and no combustible material to enter into any part of construction 
except the roofing, doors and window frames. 

External walls of reinforced concrete 5 in. thick. 

Hoists enclosure to be of incombustible construction. 

Staircases may have steps and landings of hard wood. 

The insurance companies' regulations as to fireproof doors and shutters are many 
and various, they deal with iron and steel (sliding and hinged). Metal-covered doors 
(ditto). " Check fire " doors (ditto). Ferro-concrete doors, etc. 

The openings must not exceed 56 ft. sup., and not more than 7 ft. in width or 
g ft. in height. 

In some cases not to exceed 45 ft. sup., and not more than 6 ft. in width or 8 ft. 
in height. 

In other cases 35 ft. sup., and not more than 5 ft. in width or 7 ft. in height. 

These rules generally are very careful as to fixing and little details all of the 
greatest importance. 



r jrct>N>'i'k > urrioNAi.'i 

|Aj_N (.lNt 1 l-M M. — j 



MASSACHUSETTS INSTITUTE OF TECHNOLOGY, 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reltable information -null be presented of nev> -works in course of 
construction or completed, and the examples selected will be from Ml n .,rts of the -world. 
it ts not the intention to describe these v>orks in detail, but rather to indicate their existence 
M nd illustrate their orim ,-v features, -it the most explaining the idea-which served as a basts 
for the design. 



THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY-NEW BUILDINGS. 

[ N an article in a recenl issue of the Technical Journal of Association of factors il 
is stated thai "Up to the period of the Civil War technological education n th 
Unfted Staie was represented only by the United States Military and Naval ; a«-^ 
in military engineering, bv the Rensselaer Polytechn c Institute and I nion ollege in 
CivU SSnSrinl, and by the recently established scientific departments of Harvard 
and Yale Colleges. 



ifc 2 GENERAL STUDIES 

1 3 CIV ENG. MECH ENG a 
NAVAL ARCHITECTURE 

1 4 GENERAL STUDIES 
I > 5 MECH ENG 5 NAVAL ARCH. 
1<3M6CHE'/ STRV 

\° i 7MECHANICH ENG. 

I O 8 CHEMISTRY. GEOLOGY & PHYSIC' 

I 9 MECH. ENG. ft ADMINISTRATE 
\ X 1 io PHYSICS & ADMINISTRATION. 
ISjl 12 POWER HOUSE 

17 LIBRARY ADMINISTRATION 
BIOlOGY, 8 ELEC ENG. 




Fig. 1. 



Buildings under construction, shaded lines. Future construction, dotted lines. 
New Buildings— The Massachusetts Institute of Technology. 



»« On April mth, i86i, on the very eve of the Civil War, an Act vvas passed b he 
State Legislature to incorporate the Massachusetts Institute of technology for the 
purpose of instituting and maintaining a society of arts, a museum of arts, and a school 

159 



NEW WORKS IN CONCRETE. 



ICQNCBEXFJ 



sl§3£< 




1 60 



^OON.vriMKTlONAl 
*K.N(iINM I.MNG — 



MASSACHUSETTS INSTITUTE OF TECHNOLOGY 





161 



NEW WORKS IN CONCRETE. 



[CO NCRETE 



of industrial science, and aiding generally by suitable mean- of advancement, develop- 
ment, and practical application of science in connection with arts, agriculture, manu- 
facture and commerce.' A small tract of newly-filled State land in Boston was set 
apart for the use of the new Institute, which was authorised to hold property to an 
amount not exceeding $200,000." 



flS'/l 




Fig, 5. Showing Pouring of Floor Concrete. 
Ni-.w Buildi a 1 hi. Massachusetts Institute 01 Technology. 



The Institute originally started with a single building, bul it has been necessary 
from time to time to expand il in various directions. 

Recently a further tracl of land was bought of aboul 50 aires on the Cambridge 
side of Charles River separating Boston from Cambridge. 

It is with the buildings now in course of erection on this site that we are concerned 

1 62 



(ESE5JE5BK3 Massachusetts institute of technology 

in the present notes. It is stated that I he land, with the buildings now being erected 
upon it, will cost about five million dollars. 

I Im- buildings consist entirelj oi lectu oms, laboratories, and the like, but it 

is expected that later on dormitories will be erected and other provision made l«n the 
social life ol the institution. 

It w;is to be expected that in a large building undertaking of this kind reinforced 
concrete would certainl) enter into the construction. 

Fig. i gives the general lay-out showing the buildings now under construction and 
;i1m> indicates future work to be undertaken. 

The plans for the new buildings were approved in July of last year and since that 
date work has advanced rapidly. 

By about October the excavation work was completed (a total of 65,000 yds.), and, 
w iih the exception of the library, pile driving had keen finished, some jo, 000 piles having 
lx.n driven. Further, about [5,000 cu. yds. of concrete had keen poured, 600,000 sq. fi. 
oi forms had keen erected, and 1,000 tons of reinforcing steel placed. 

Considerable progress had keen made on the work between October and the 
beginning of the current year, when practically three-fourths of the concrete work for 
all the buildings, including the library, was completed, 

Tke accompanying illustrations show the work at different stages of construction 
and will give some idea of the extent of the scheme. We hope to be able to supplement 
the present preliminary notes by a fuller article at a later date. 

The work is being carried out by the Stone and Webster Engineering Corporation, 
of Boston, to whom we are indebted for our illustrations and some of our particulars. 



163 



MEMORANDA. 



KDNCBEXE1 




Memorandaoand News Items are presented under this heading, -with occasional editorial 
comment. Authentic neios toill be welcome. — ED. 



The Institution of Civil Engineers. — At a meeting of the Institution last 
month Mr. F. I). Evans, A.M.Inst.C.E., read a paper, entitled " Engineering 
Operations for the Prevention of Malaria," and we give the following short extract 
from the paper : — 

Anything which relates to the health of communities and labour forces is of 
importance to engineers, but the disease referred to in this paper, malaria, is of 
particular interest to them. The effects of malaria are often terrible, and may lead 
to very high death-rates. Its effect on works in new countries is to greatly increase 
their first cost and cost of maintenance, and it may lead to their abandonment. 

Malaria occurs more or less in all warm climates, and is caused by parasites of 
the blood which are injected by anopheline mosquitoes. These mosquitoes first take 
the parasite from infected man when sucking blood. Thus part of the life of the 
parasite is spent in man and part in the mosquito. Quinine is the remedy for malaria. 
No attempts to transmit malaria except through the agency of mosquitoes have been 
successful. 

The most important method of reducing anophelines is by drying land by means 
of thorough drainage. In hill-land subject to heavy rainfall such work presents many 
novel problems, but has been successfully accomplished in the Federated Malay States 
at a reasonable cost. 

Ravines in the Malay States, unless exceptional, can only be laid dry by a con- 
tinuous drain running completely round the hill-foot, cut on a line at a little above 
the wet surface level. Open earth or masonry drains are useless for the purpose, and 
it has been found that the only way to construct permanent hill-foot drains is to use 
agricultural drain-pipes as subsoil drains, and to provide outlet drains of open masonry 
or subsoil pipes to carry off their discharge. The pipes are proportioned to run not 
more than one-quarter full in ordinary dry weather (one-fifth full for drains over 6 in. 
in diameter). The use of pipe drains less than 4 in. in diameter is not ordinarily 
advisable, owing to the liability of their choking. The pipes are laid at a depth of 
\ ft. to 4 ft. (or even deeper on steep slopes); they have been laid at the heads of ravines 
on slopes of 1 on 3 with satisfactory results. 

Trees must be removed from the vicinity of pipe drains, as their roots may grow 
into and (hoke the pipes. Undergrowth and long grass should not be allowed to 
grqw up, for the same reason. 

As economy is ;ill-important in anti-malarial work, it is rarely possible to provide 
masonry drains large enough to carry all flood-water, and these are, therefore, usually 
calculated to run one-sixth to one-fifth full in ordinary dry weather, and are surcharged 
during Hoods. An inexpensive and thoroughly efficient type of drain has been evolved 
to meet the conditions, formed of concrete blocks of half-egg shape, laid close but 
unjointed. The blocks are laid without foundations even on had ground in flowing 
water. Should thev move out of line or gradient, it is easy to reset them correctly 
when the surrounding ground has settled, after which they give no trouble; but 
resetting is rarely necessary. 

Iron and Steel Institute. — The annual meeting of the Institute will be held, 
by kind permission, at the Institution of Civil Engineers, (heat George Street, London, 

1 64 



1 



„ (."ONM 1'UCTIONAl 
hNC.lNMWlNC, — , 



MEMORANDA 



S.W. on Thursday and Friday, Maj 13th and 14th. Thursday, Maj iv'b has been 
fixed provisional!) as the date foi the annual dinner. 

It has been decided for 1 1 1 « * present to hold the autumn meeting in London during 
the vs eek ending September 25th. 

The King George Hospital.— We rtote from the daily press that II.M. Stationer) 
Office, regarding which two articles appeared in 0111 Journal, is to l>e turned into a 
hospital for the wounded soldiers from the front. 

As t ;m well be understood, a good deal ol work is necessary to convert this large 
and extensive building, originalh intended for the Stationery Department, into suitable 
quarters for hospital work. The following are a few particulars regarding iliis 
hospital : 

On the fifth floor the special feature will be a l<»n^ row of kitchens, whence the 
Uhh\ will be sent l>\ lifts in heat-preserving receptacles to the ward kitchens, of which 
each lower floor will have seven. On this floor are also two dental rooms, and there 
will also be a number of beds. 

The second, third, and fourth Poors will be given over to beds, mostly for surgical 
cases. Each of these floors will have two operating theatres. 

On the ground floor will be the administrative offices, barrack room, a recreation 
room, dispensaries, and laboratories. 

In the basement there is to be a well-equipped department for X-ray apparatus, 
and there will also be storage room. 

The llat roof, too, will be turned to account, for it is to serve as an open-air 
recreation ground when conditions permit. 

Altogether this vast building will have 63 wards, 1,650 beds for patients, and six 
operating theatres. 

The Improvement of the River Trent. — With the object of improving the 
navigable facilities of the River Trent below Nottingham a scheme which will 
involve the expenditure of about ^160,000 has recently been decided upon. The 
scheme comprises briefly the deepening of the river between Nottingham and Newark 
and the provision of locks in order to make the former city an inland port accessible 
for larger boats than can at present use it between this place and the River Humber. 

The necessary powers were obtained in 1906 to construct additional locks and 
weirs beyond those already carried out under former powers obtained. Under the 
powers of icjob the Cromwell lock was built. It is 188 ft. long between the gates and 
30 ft. wide. These dimensions were adopted in order to provide accommodation at 
one time for four of the present standard Trent boats or one tug and three boats, as is 
customary in the navigation of the river. The sills of the gates are placed at such levels 
as to ensure in any dry period a minimum depth of water of 6 ft., and the walls and 
gates are carried to a sufficient height to enable the lock to be navigated in flood time. 
A weir has been provided with shutters. 

Practically the whole of the work was carried out in Portland cement concrete, the 
ballast for which was obtained from the excavation for the lock. 

The walls have a maximum height of about 30 ft. from the bottom of the founda- 
tion to the coping level, and were built in heavily timbered trenches. 

The present proposal comprises numerous new works, including additional locks 
and weirs, and also a large goods depot on the canal side in Nottingham. 

The new works will be carried out by Mr. F. Rayner, A.M.Inst.C.E.j the engineer 
to the Trent Navigation Company, in conjunction with the City Engineer of Notting- 
ham. — Taken from an article in the Engineer. 

Loughor Bridge. — At a recent meeting of the Carmarthenshire County Council 
it was reported that the Loughor Bridge Joint Committee have decided to erect a new- 
bridge at Loughor in reinforced concrete. The bridge is to be (-170 ft. long between 
abutments and 36 ft. wide between the parapets, having a 24-ft. carriageway and two 
6-ft. footways. There are to be seven intermediate piers, the foundations for which 
are to be carried on piles in the river bed, the piers themselves being formed of re- 
inforced concrete. The main structure is to be carried from pier to pier by means of 
six ribs and the slab is turned up at the sides to form a parapet. 

The tender which was accepted was that of the; Midland Counties Reinforced 
Concrete Company, of Birmingham. 

E 16; 



MEMORANDA. 



iCQiNci2n:m 



PUBLICATIONS RECEIVED. 

Reinforced Concrete Construction. — Messrs. F. A. Macdonald and Partners, 
reinforced concrete engineers, have recently issued a most useful handbook dealing with 
their system of reinforced concrete construction. In addition to setting out in a very 
clear and concise manner the advantages claimed for their system, the handbook also 
contains much other useful information. Some general notes are given regarding the 
properties of reinforced concrete, notes as to bending moments, and also calculations 
for beams, columns, and foundation slabs. A general specification for the practical 
execution of reinforced concrete work is also given. The book is well got up and 
contains a large number of very good illustrations with short descriptions of works 
carried out on the Macdonald system. The book will be forwarded to engineers and 
architects upon application to Messrs. F. A. Macdonald and Partners, 135, Wellington 
Street, Glasgow. 

Lockwood's Price Book, 1915. — This book is so well known among architects, 
surveyors, and others that it is almost needless to emphasise its utility. In the preface 
special attention is drawn to the greatly increased price of wood goods on account of 
the decrease of wood imported, due to the war. Further, wages have increased, and 
the section dealing with the price of labour has been brought up to date as far as 
possible. 

Everv kind of building work is dealt with. There are a number of appendices 
containing tables of weights and measures; particulars regarding solicitors' costs for 
conveyances, leases, etc., and stamp duties; valuation tables, wages tables; form of 
agreement for building contracts sanctioned by the R.I.B.A. Further, the London 
Building Acts and the various Amendment Acts, 1894-1909, are given in a supplement, 
including the L.C.C. (General Powers) Act, 1905, prescribing regulations and require- 
ments for steel frame and reinforced concrete buildings. 




THE 



VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum J-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 

The VICTORIA 



is built to last 



WRITE FOR CATALOGUE No. 29. 



THE 



T. L. SMITH Co. 

13, Victoria Street, S.W. 



166 



Please mention this Journal ivfien inviting. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume X. No. 4. London, April, 191 ! 

EDITORIAL NOTES. 



ECONOMY IN REINFORCED CONCRETE CONSTRUCTION. 

Elsewhere in this issue we publish an extracl from a paper which was read 
before the Concrete Institute by Mr. T. A. Watson, together with some notes 

of the- discussion thai followed. There are many who arc quite assured thai 
;i real and substantial economy (-an be effected with the use of reinforced con- 
crete, and the great increase in popularity during recent years goes to prove 
thai the material is capable of competing successfully with steelwork in price, 
s >eed of construction and adaptability. 

Again, there are many persons connected with the building industry who 
arc just as convinced that reinforced concrete is considerably over-rated, and 
the} will produce estimates which indicate the absence of any saving with the 
material. These persons are quite honest in their convictions, and not biassed 
by an) financial interest in material or firm. This may seem strange and 
unaccountable to anyone who has no knowledge of the methods which obtain in 
the building industry, but when all the facts and conditions are analysed it is not 
so surprising, and is cnlv indicative of the lack of a definite relation and method of 
business between client, architect, specialist and contractor. There are many 
architects who claim to have considered the question of cost by actual tenders for 
the two materials, and yet if the facts of the matter were known it would be found 
that no real comparison could be drawn, as the same basis had not been adopted 
when obtaining the tenders, and the architect, often not really wishing- to use rein- 
forced concrete, will put conditions and difficulties in the way of economical design 
which he does not consider necessary in the case of steelwork. A certain archi- 
tect was heard to state a few days ago that personally he considered a factor of 
safety of 10 was necessary in reinforced concrete work, as it was impossible to 
guarantee the small amount of steel being placed in exactly the right positions 
and therefore the material was unreliable ! With steelwork he was satisfied 
that it was impossible for any errors to be overlooked, as the work was more 
open to inspection for a fairly long period of time. This gentleman also stated 
that he had always found steelwork construction as economical in first cost as 
reinforced concrete. We should quite imagine that anyone requiring a factor 
of safety of 10 in the case of the latter material as against a factor of 4 in the 
former would find steelwork much cheaper. It is obviously quite impossible to 
compare the relative cost of the two materials when the tenders are obtained 
in a casual sort of a manner without due regard to economical and efficient 
design in both cases and without imposing suitable conditions for each scheme 
which are fair to the material. Generally speaking, it is the architect who will 
settle the construction to be emploved, leaving out for the moment those 

167 



ECONOMY IN CONCRETE CONSTRUCTION. ^^OTCTE 



schemes which arc executed by the contractor direct for the client, and it is 
necessary that this fact should be realised at the outset, because' it has an 
important bearing- on the subject. 

Now, if architects as a body could be convinced that an actual saving is 
effected by the use of reinforced concrete, there is no doubt that structural 
steelwork would at once take second place in all important work, but there 
are difficulties to be overcome which must not be overlooked. In the first 
instance, architects are familiar with steelwork, and can generally calculate 
the required strength of ordinary members with the aid of available tables, 
and they have a certain feeling- of confidence in dealing with a material which 
they understand. With reinforced concrete the circumstances are different, 
there being- extremely few architects who thoroughly understand the theoretical 
side of this material, and there are no tables or " rule-of-thumb " methods for 
making- even approximate calculations ; and as they cannot bei expected to take 
up the subject in the same manner as the engineer, and become proficient in 
the design, they are apt to avoid the material as much as possible. 

Secondly, the architect is not limited by any patent system if he decides to 
use steelwork. But with reinforced concrete he is limited to a certain extent by 
systems, by specialists who wish to take off their own quantities, by licensed 
contractors, and by other questions which are not helpful. If he selects a 
paiticular firm of specialists he eliminates competition, which he must have for the 
satisfaction of his client ; and the only alternative is to employ a consulting engi- 
neer, who will prepare a scheme upon which to obtain estimates. This method is 
by far the most satisfactory, but it is not always possible to persuade the client to 
pay the necessary fees to the engineer, and the architect cannot afford to pay 
them himself. We quite agree with Mr. Watson's remarks as to the great waste 
which occurs when several firms are asked to prepare calculations and schemes 
for the same building when only one set of drawings will be used. If it were 
only possible to accomplish, it would pay all the specialists to combine, in the 
case of competition schemes, and jointly employ one independent engineer to 
prepare a set of drawings upon which each firm could tender. The result 
would be lower prices and a proportionate increase in the use of reinforced 
concrete, which would eventually be beneficial to all the firms. 

Wc feel that these questions of the relation between the architect and the 
specialist, and the methods of obtaining schemes and prices, are far more 
important when considering the relative economy of reinforced concrete than 
any other points mentioned in Mr. Watson's paper, and if the material is to 
ne universal some satisfactory methods must be devised to deal with these. 
Reinforced concrete is very adaptable, but it will not always prove cheaper than 
structural steel, although some enthusiasts hold this opinion. The greatest 
CCOnom) will always be effected where a large amount of repetition in the 
n < ml,, rs is possible and where the condition's allow them to be designed with the 

economical percentage of steel. If reinforced concrete is designed by an engineer 
who is conversanl with economical and good design, there is no doubt thai a real 
economy will be effected by the use of this material as compared with ordinary 
structural steelwork, provided the circumstances of the ease permit the designer 
to take full advantage of the special properties of reinforced concrete. 
168 



[j, CONM kUKTIUN A 1 
tVKN(ilNhl-.miNCi — 



NHW WING. BRISTOL GENERAL HOSPITAL. 




rr- T-rmm 

■ 



j ifc . SSB5 B 3S vi i x . .-i T riy: ■!: 

BRSj REINFORCED CONCRETE 
M f AT THE BRISTOL 



j By ALBERT LAKEMAN, M.S.A. 




■HBH 



7*ne following description of the Extension Works at the Bristol General Hospital is 
one of the examples in building work where concrete has been used throughout, inasmuch 
as reinforced concrete has been used for the constructional members and concrete blocks 
form the external walls.— ED. 

The extensions that have just been carried out at the Bristol General Hospital 
comprise the erection of a new wing approximately 176 ft. long and about 
40 ft wide, and reinforced concrete has been employed for all the constructional 
members. The position of the new wing is a very good one, and the wards 
are placed axially north and south, so as to receive sun all day. There are five 
floors in all — viz., basement, ground, first, second and third, and the basement 
floor is only partly below the ground surface level. 

The accommodation in the basement consists of a large dental department, 
with surgeries, waiting rooms, conversation room, workroom and offices- 
and dining-room accommodation for the female staff. A new laundry is also 
provided on this floor with all the necessary departments and appliances. 

The ground floor is devoted to six suites of private sitting-rooms and bed- 
rooms for resident officers, smoking and common rooms, messrooms, regis- 
trar's room and sundry offices. 

On the first floor the space is allocated to a women's medical 25-bed unit, 
comprising a ward of 22 beds with sun balcony at the south end, one single-bed 
ward and one two-bed ward, sister's room, ward kitchen, larder, and the neces- 
sary rooms for storing linen and patients' clothes. 

A sanitary wing is also constructed as a small block off the wing building. 
On this floor there is also a clinical laboratory. 

The second floor is designed so that it can be converted to provide exactly 
the same rooms as mentioned for the first floor, but at present it is arranged 
as a maternity ward, with a large open-air balcony at the south end. A part of 
the building is roofed in at the third floor level with a flat roof that can be 
utilised as a garden or open-air exercise space, and the remainder of the third 
floor is given up to sleeping accommodation for the nurses. Twenty-two addi- 
tional bedrooms have been provided, some of which were obtained by an exten- 
sion of the top floor of the existing building adjacent to the new wing-. 

The whole of the constructional members are of reinforced concrete on the 
Hennebique system from the detail drawings of Messrs. Mouchel and Partners, 
38, Victoria Street, Westminster, and the building is a complete concrete struc- 
ture, as the whole of the external walls are built of concrete blocks made on 
" W'inget " machines. 

r 169 



ALBERT LAKEMAN. 



ICONCREXEi 




O 




I70 



j„ OONM U'l IIT1UN A 1 | 




B 2 



NEW WlNG t BRISTOL (;!<X1-RAL HOSPITAL. 

Columns. I llr columns are ai 
ranged generally in two longitudinal 
rows, .Hid the) occur in the outci 
w^lis, thus leaving the whole ol the 
flooi space clear and available lor an) 
internal division. These two rows are 
about 38 ft. apart ;ii thai end of the 
wing adjacent to the old building and 

about 29 It. apart lor the remainder ol 
the length. In the basement a row ol 
secondary columns is formed about 
18 ft. from one of the main rows on 
the outside of it, owing to the width 
of the basement floor being greater, 
for a portion of the length, than the 
floors above. The spacing of the 
columns is about 16 ft., centre to 
centre, and at the south end they are 
aranged on the cireumferenee of a 
semicircle at about 7 ft. centres to 
carry the curved balconies which are 
provided at the end of the building. 
The columns vary in size according 
to position and load, and the largest 
section employed is 24 in. by 24 in. 
with eight lines of vertical reinforce- 
ment tied with links at 4-in. centres. 
The load on the soil was taken at 
4 tons per sq. foot, and the reinforced 
concrete foundations to the columns 
were carried down some distance 
below the basement floor level on 
account of the nature of the soil. The 
largest bases are about 8 ft. sq., and 
these are about 21 ft. below the base- 
ment Moor, which is slightly less than 
the maximum depth of 24 ft. employed 
in some cases. 

Beams and Floors.— A plan of 
the basement floor, showing the gene- 
ral lay-out of the beams, is illustrated 
in Fig. 1, where it will be seen that 
the main floor beams span the width 
of the building and are carried by the 
two longitudinal rows of columns 
above mentioned, while secondary 
beams are introduced between at 
about 5 ft. 6 in. centres. The main 

171 



u c 

o X 



in 

£Q C 

H 

C £ 

R <* 

5 23 



_ o w 



U X 

r. < 

1 w 



^ o 

u 



fe * 



ALBERT LAKEMAN. 



iCQNCBEXFJ 



beams arc of two types, viz., those ha\ ing a span of about 38 ft. and those 
aeross the narrower portion of the building-, whieh have a span of about 28 ft. 
The first mentioned have a total depth of 27 in. and a width of 12 in., with six 
bars in the lower surface and three in the upper at the centre, one half of those 
in the lower surface being bent up towards the top at the ends. Vertical stirrups 
are provided to both sets of rods throughout the length of the beam. One of 
these beams, which supports a larger floor area than the others, has six bars on 
both the upper and lower surfaces. The second type of main beam has a depth 
of iq in. and a width of 8 in., with four bars in the lower surface and two in the 
upper. A detail showing the connection between two of these main beams and a 
column is illustrated in Fig. 3, where the arrangement of the bars can be clearly 
seen. The secondary beams are 16 in. deep and 6 in. wide, reinforced with two 
bars in the lower surface, and the floor slab is 3 in. thick only, with rods in both 
upper and lower surfaces. The type of floor here employed does not follow that 
used in the other floors, as will be seen later. A somewhat curious beam is that 
illustrated in Fig. 2, this having a span of 
about 20 ft. and occurring at the junction of 
the sanitary block and the main building. 
The bearing at either end is at different 
levels, and it is, therefore, cranked in its 
length with a horizontal top surface and a 
partly horizontal and partly sloping soffit. 
Owing to the expense of carrying down the 
walls to the required depth to obtain a satis- 
factory bearing, as in the case of the 
columns, these are carried at a level just 
below the basement floor by beams between 
the columns, as shown in the detail illus- 
trated in Fig. 4. These beams generally 
are designed as tee beams with a total depth 
of 19 in. and a 9-in. rib and 30-in. flange 
with lour bars as reinforcement on the lower 
surface. In some cases it was necessary to project the portion of the flange on 
one side of the rib for a greater distance owing" to projection beyond the main 
face of the wall, and such portion had to be calculated as a cantilever slab. The 
tailing down is provided by the beam taking the vd^v of the floor which runs 
parallel If; the wall coincident with the inner face of the columns. 

The construction for the upper floors is somewhat different to that just 
described, as il consists of main beams transversely across the building between 
the columns, and the bays so formed are filled in with a light floor composed of 
reinforced con< rete and hollow concrete tubes on the Hennebique system. The 
main beams on the widest portion of the building are 23J in. deep and i(> in. 
wide with eight rods in the lower surface, and in the narrower portion they are 
2^\ in. deep and 12 in. wide with four bars in the lower surface, and in some 
cases two bars are provided on the upper surface in addition. A portion of the 
giound floor at one side is roofed in with a sloping roof and a detail of the 
sloping beams, the main beam in the adjoining bay and the connection with the 




Fig. 4. Detail of Lintel Beam. 

Reinforced Concrete at the Bristol 

General Hospital. 



(§ 



„CDN>TUlK-riONAlJ 
KNOIMt.IRlNCt - J 



NEW WING, BRISTOL GENERAL HOSPITAL. 



column is shown in Fig, 6. The sloping beam is is in. deep, _• \ in. wide 
across the flange .-it the top, and i 2 in. wide across t lu- rib, and it is reinforced 
with eight rods, lour in each surface, for the greater part of its length. The 
floor panel construction is of three types to suit the differenl sizes of the b;i\s. 




The smallest type has a constructional thickness of 8 in. with tubes at 18 in. 
centres and a minimum thickness of 1 1 in. of concrete over the tubes. The other 
types are 12 and 14 in. deep respectively, with tubes at 24-in. and 28-in. centres. 
The tubes are placed 3 in. apart on the clear at the top, and with the sloping 
sides this gives a thickness of 4 in. of concrete at the bottom, and the concrete 



'73 



ALBERT LA K EM AN. 



(CDNCRETFJ 




is reinforced with two bars on the 
lower surface at the centre of the 
span. One of these bars is cranked up 
towards the top and the other is con- 
tinued right through in the lower sur- 
face. Bars are also placed in the top 
surface over the tubes and at right 
angles to them. These floors are very 
light for their strength, and the shut- 
tering- required is reduced to a mini- 
mum as the tubes act as a permanent 
centering- to the greater part of the 
concrete. 

External Walls. — The external 
walls are carried by lintel beams be- 
tween the columns at the floor level, 
these walls being built with an outer 
leaf of 9 in., constructed of hollow 
concrete blocks, a 3-in. cavity, and an 
inner leaf of brickwork 4^ in. thick. 
The exterior treatment of the building 
with the concrete blocks is very satis- 
factory, as will be seen in the photo- 
graphic views in Fig. 5, while the 
construction is lig-ht and durable. 
The shafts that can be seen in this 
view, and which extend above the 
roof level, are used as extraction 
shafts in connection with the ventila- 
tion. They are formed in reinforced 
concrete and generally have a thick- 
ness of 6 in. with bars in both sur- 
faces and in both directions. The 
interior is readily accessible and can 
be hosed down when required. The 
open air balcony which occurs at the 
south end of the wing is carried at 
each floor level by curved lintels 16 in. 
deep and 9 in. wide, reinforced with 
two bars in both upper and lower 
surfaces. 

Laundry. — An interior view of 
the laundry is given in Fig. 9, this 
being a one storcv building with a 
height of about 12 ft. The founda- 
tions are carried down about 6 It. 
below the floor level and the walls are 
carried on reinforced concrete slabs 



'74 



1 



, oorwiMirnoNAi 



NEW WING, BRISTOL GENERAL HOSPITAL 



8 in. thick and a It. or _• ft. 6 in. wide, these being reinforced in both surfaces. 
The columns are 9 in. and 1 _• in. square with four lines oi vertical reinforcement, 
aii'l the largei type has a foundation slab 5 ft. square with :i minimum thickness 
of 8 in. .it the outei edges, in< reased to -*<> in. al the point <>l Intersection with 




Fig. 7. View of one of the Corridors. New Wing. 
Reinforced Concrete at the Bristol General Hospital. 

the column. A lattice of rods is placed on the bottom surface and at the centre 
ol the thickness with the main column rods turned out at right angles to the 
length, 2 in. above the bottom reinforcement. The roof is constructed with 
arched reinforced slabs springing from 16 in. by 9 in. reinforced concrete beams, 
with a central skylight running- through each bay, and tie beams are provided 

175 



ALBERT LAKEMAN. 



[CONCBETFJ 



across the bays at intervals of 7 ft. 6 in., these being- 18 in. deep and 7 in. 
wide. These beams come above the slabs between the skylights, and holes are 
formed through them for the passage of water in the gutters. The whole of 
the roof and beams are covered with asphalt. 




Generally.— The floors of tin- wards are finished with leak boards, and 
the walls generally are covered with Keene's cement finished with enamel. 

1 76 



r J, lONMlHJCTIUNAl 
IAkN(.1NKKW1N(. — 



NEW WING, BRISTOL GENERAL HOSPITAL. 



Many improvements have been carried out generally, apart fn m the construction 
of the nev< w ingf. 

The hot-water service <>i the whole hospital has been centralised and con- 




verted into the indirect system, with a view of effecting economy and obtaining 
higher and more uniform temperature. The heating of the new wing is by 
low-pressure hot water, accelerated by means of an electrically driven pump, and 
in the large wards this is supplemented by open fires in the centre of the room. 



i-- 



ALBERT LAKEMAN. 



ICQNCBETH 



The radiators arc of the " Hospital " type with fresh air inlets at the back fitted 
with internal shutters for regulating the admission of fresh air, and designed so 
as to be readily removable for cleaning purposes. 

The ventilation is by natural means, consisting of opening windows and 
the extraction shafts previously mentioned. 

A water-softening plant has been installed having a capacity of 1,000 
gallons per hour. The softened water is used for the hot-water supply, laundrv 
purposes, and boiler feed make-up. It is estimated that the introduction of 
this plant will save something like 50 per cent, in the cost of soap and 35 per 
cent, in the cost of soda. 

The contractors for the reinforced concrete work and for the building 
generally were Messrs. Cowlin and Sons, and the heating, hot water, and 
water-softening installations were executed by Messrs. G. V. Haden and Sons, 
of Trowbridge. 




Fig. If. View of another Corridor in West Win^. 
Reinforced Concrete at the Bristol Genkral Hospital 



7« 



ll 



.I'ONMI'IKTIONAL 
*LN(.1NI.I k'INIi--; 



MOMENT (>!■' INERTIA OF CONCRETE SECTIONS. 




1 



MOMENT OF INERTIA OF 

REINFORCED CONCRETE 

SECTIONS. 



sr-- ; . 



By JOHN A. DAVENPORT, M.So, A.M.Inst.C.E. 

The following article toill doubtless prove of interest to engineers and others 
studying various theoretical problems in connection "with reinforced concrete.- ED. 



The moment of inertia is a particular case of second moment, and applies to both 
masses and areas. Applied to masses, it is a perfectly legitimate term, as they possess 
inertia; hut the same cannot be said of areas, which do not possess inertia. 1 he 
reason for the apparently anomalous use of the term, " Moment of inertia oi an area, 1 
will be understood from the following condensed derivation of the moment of resistance 
of a section of homogeneous material. The complete discussion will be found in text 
books on Applied Mechanics and Theory of Structures, but a statement of the assump- 
tions made will not be out of place here. They are : — 

1. Plane layers remain plane. 

2. Hooke's Law is true. 

3. Young's Modulus the same for tension and compression. 

4. The elastic limit is not exceeded. 

Referring to Fig. 1, in which A O B is an end view of the section considered, 
we have — 

& = l (1) 

v. y 

/", and / being stresses at points which are distant y, and y, respectively, from the 

neutral axis. Thus, at a distance y from the 
neutral axis the stress is — 




y\ 



y 



(2) 



and the small area subjected to this stress can 
be called 8 A. The total force on this area 
is then — 

/i 



fHA=^y8A 



(3) 



The moment of this force about 0, a 
point in the neutral axis, will clearly be — 



_/i 



(4) 



Fig. 1. 



8R = Jly2§A 

Vl 

which is the moment of resistance of ihe stress 
on the elementary part (S .4 of the whole 
section. The moment of resistance of the 
whole section is obtained by adding up all the 
elementary terms similar to that shown in (4), 

'79 



JOHN A. DAVENPORT. [ CONCRETE] 

so that — 

# = 28#=2 - /] r S A = & Z r L '8^ (5) 

v, Ji 

It should be noticed that (5) is a summation over the whole area, rendered possible 

by the fact that the stress line COD, Fig. 1, is continuous. If the element 6 A were a 

mass 8/7/. then the factor "SyPStn would be denned as the moment of inertia of the 

mass, a perfectly logical definition in view of the fact that masses possess inertia. By 

analogy, the factor ~Ly 2 5A in (5) is called the moment of inertia of the area or moment 

of inertia of the section, so that the moment of resistance may be written — 

R= f] I or tl (6) 

v, y 

Another equation, which involves the moment of inertia, may be easily deduced, viz.— 

*-=_!_ (7) 

E I Rad. 

in which E is Young's Modulus for the material, and Rad. is the radius of curvature of 

the beam or other piece subjected to bending. 

These expressions, (6) and (7), are the fundamental flexure equations, and /, which 
occurs in each, is the " Moment of inertia of the section about the neutral axis." 
Further, the moment of inertia depends upon, and follows, the derivation of moment of 
resistance of the section, which, in turn, is based upon the assumptions made and already 
given. Shortly stated, the moment of inertia of any section must be taken about the 
neutral axis, and must be consistent with the assumptions made in working out the 
theory of bending, for both homogeneous and heterogeneous materials. 

The assumptions upon which the reinforced concrete theory is based are as follows :— 

1 . Plane layers remain plane. 

2. Hooke's Law is true. 

3. The tension steel takes all the tension. 

4. The bond between steel and concrete is perfect. 

5. The elastic limits are not exceeded. 

6. There are no initial stresses. 

As a result of these assumptions it can easily be shown that, except in isolated 
cases, the neutral axis does not pass through the centre of gravity of the concrete 
section. In fact, for single reinforcement, the position of the neutral axis is a function 
of the amount of reinforcement ; while for double reinforcement, which will be fully 
discussed later, it is a function of the amount of steel, its position in the compression 

. and the depth of the section. Yet in dealing with the moment of inertia of 
reinforced concrete sections, books known to the writer all assume; that the neutral axis 
passes through the centre of gravity of the concrete section. Taking the expression 
given in Appendix V. to the 2nd R.I.B.A. Report as the best known, we are given, for 
rectangular sections only 

/=— A d- + ■ im-l)A v dl (8) 

12 4 

[f we take equal tension and compression steels, as invariably the case in columns, 
and call r, either the percentage tensile; or compressive steel, then — 

1 -Zi™ or A v =^ (9) 

2 100 50 

Substituting this value of A v , along with /// = 15, and A bd in (8), we get 



and the modulus ol section i; 



I So 



1= ] bd 3 + 7 rlbddl (10) 

12 LOO 

S„, ' bd--V -- r x bdl (11) 

6 50 



fo, CONJTIMICTIONAE 



MOMENT OF INERTIA OF CONCRETE SUCTIONS 



It is not the object of (his article to investigate ever) aspect of tins question ol 
moment of inertia of reinforced concrete sections; but rather to point out the dis- 
crepancies in the expressions generally regarded at the present moment as correct ; to 
deduce a corred expression for one particular type of reinforced section; and to 

compare the results obtained from the former and latter expressions. ( )n this account a 
doubly* reinforced section with equal tension and compression steels will be considered, 

because — 

Firstly, by far the Larger number ol column sections are of this type. 
Secondly, a doubly reinforced section with equal tension and compression 
sleds, symmetrically displaced, has the same moment of inertia both betwe< a 
and outside points of contraflexure, if the full area of steel be continued 
throughout. Thus the expression may be inserted in deflection equations. In 
the ease of singly-reinforced beams the presence of contrary bending at any 
P out automatically makes the moment of inertia zero, as the concrete is not 
assumed to be able to take any tension. 

Thirdly, arches are invariably made of this section, and in the case 
of statically indeterminate arches 
it is necessary to use the moment 
of inertia, and 

Fourthly, the doubly-rein- 
forced section may be said to be 
the general case and to include 
also the singly-reinforced section. 
Several cases present themselves de- 
pending upon the amount of cover to the 
reinforcement, and different conditions are 
provided by varying the ratio between the 
areas of tension and compression steels. 

In the following investigation it will 
be assumed that the areas of tension and 
compression steel are each equal to A f , 
and that the cover to the steel is 2 in. 
Using the standard notation and referring 



12) 



to Fig. 2 we have — 

Stress in compression steel = 

n-2 

c s — in c 

;/ 

Considering unit width of section, 

Total P ush^ C ^ + A t c s = c\ } i+-^f(m-l) { n -2)~\ 
I \-L 100// J 







A c 


C 






j ' 


1 
• '"CM 
1 


r. / ' 


1 


A 


1 








M r 


c 


1 

N 
* i 

1 t 


! 


V 




\ 


t 


/ Neural 


Axis 








; 

S 




: 








T3 




\ / 


1 




' 


L_ ■ 


-f, 


<t 



D 



Fig. 2. 



(13) 



(14) 



allowing for the reduction of the concrete area by the presence of steel. 
Xd—ri) m i\ d 

Too 

: - ' • Equating (13) and (14), and putting m=15 and n=ri d, we get: 

50 «'* d+ 29 ri r x d— r (15*2+28) = (15) 

A quadratic giving n\ the dimension which determines the position of the neutral axis, 
as a function of r, and d. The solution of (15) is : 



Total pull = Aft = 
as t = mc 



- 29 r, d + \ 8 41; ,-^- + 30007, ^ + 5600 r, d 
lOOd 



{A 



181 



JOHN A. DAVENPORT. [CONCRETE^ 



Equation (A) gives n for all values of /-, and d x with 2 in. cover to the reinforce- 
ment, but is rather awkward to use in its present form. The following expressions are 
much easier and sufficiently accurate for all practical purposes — 

For '", = 1, i.e., 1 per cent, tension steel and 1 per cent, compression steel, 

„' = 0'33 + ^ (4) 

d 

Forr i = 2 ' ;,' = 0-388 + ^ (A,) 

d 

Forr i = 3 - ;/' = 0-418 + °^ U,) 

d 

For; '^ 4 ' ,i' = 0-435 + °™ (A 4 ) 

For; ^ 5 ' « ' = 0-448 + ^ 3 (A-) 

d 

Turning now to the derivation of moment of resistance, from which an expression 
for moment of inertia can be obtained, we have — 

If /be the stress in the concrete at a point distant y from the neutral axis, then, 
see Fig. 2. 

f=-y (16) 

n 

and this acts on an area 5^4, so that the moment of the force on this area is— 

dR ci =yfdA=£y 2 6A (17) 

n 

The total of such elementary moments is — - 

R cl = 2 5R c ,=-2y'8A = C I cNA (18) 

// // 

in which I b na is the moment of inertia of the concrete compression surface or area 

about the neutral axis. For unit width this can be shown to be — , so that 

D _ c n 3 _ en 2 , . 

Rei--— — — (19; 

n 3 3 

As the compression steel is concentrated at a point n — 2 from the neutral axis, the 
moment of this force about the neutral axis is 

Rc8= (m-l)cA i {n _ 2r=: 7 cfjd^^y (2Q) 

11 50 ;/ 

r d . 

by putting m = 15, At= — — , and allowing for the reduction in the area of compression 

concrete. 

The tension steel is distant (d — ii) from the neutral axis, and the moment of 
resistance is therefore 

R,s = A,t(d-n) = ^- ri ^ (d-iif (21) 

20 n 

The total moment of resistance of the section is 

R = R cl +R ca +Rt,, or 

C ir 7 c r, d . .„ , 3 r, dc , , \% lnn ^ 

R = -^T+m ;/-2"+^ Ul-n) (22) 

3 50 » 20 ft 

Taking out a factor , this becomes 
// 

C ["«' .29 . , 14 . , 14 . , 3 ,,3 



C [n 29 .14 14 ,3 ,3 . -I 

= » L 3 + 100 ,v/;r " 25 r ' r/,/ f 50 '*' ' H ~ 20 '"' <* ~ 10 n d " J (23) 



1*2 



l77coNyikM)rnoNAT| MOMENT OF INERTIA OF CONCRETE SECTIONS. 

(WN(,1M I 1,'INO —J 



This is in tin' sun ■ Form as (6), c being the stress in the i oni r< te al a point dii tanl 
/; from iln- neutral axis. The moment of inertia is therefon 






. 3 . M 
I [q r x d n 25 r \ dn 



] I 
50 



r.d 






Putting n >i' <i in (2 I ». we gel : 

V 3 LOO 20 10 / 25 50 

This is the general expression For momenl of inertia, per unit width, when the covering 
concrete is J in. and the tension and compression steels are equal in area. The momenl 
of inertia For the Full breadth is given by multiplying (II) by the breadth h of the section. 
Expression (B) may be simply written — 

l=xd*-yd*+zd (/*,) 

A form which is easy to use it" the factors x, y, and z be known. 

The Following table gives values of the factors //', x, y, and z, calculated from the 
i xpressions (.4 ,) to iA :< ) and (/>). 

Table of n', x, v, and z. 



p=i 



IO 


0-373 


0*09575 


0-2089 


0-28 


20 


u\15 2 


0-09487 


0-1991 


0-28 


30 


o-344 


0-09469 


0-1926 


0-28 


40 


Q-34 1 


0-09464 


0-1910 


0-28 


5° 


o*339 


0-09462 


0-1898 


0-28 



p=2 



IO 

20 

3° 
40 
so 



°'444 
0-416 
0-407 
0-402 
o-399 



0-17712 


0*4973 


0-56 


0-17477 


0-4659 


0-56 


0-17435 


°-455 8 


0-56 


0-17418 


0-4491 


0-56 


0-17404 


0-4469 


0-56 



P=3 



t = A 



P=. 



10 


0-480 


0-25531 


0-8064 


0-84 


20 


0-449 


0-25146 


o-7543 


0-84 


30 


°'439 


0-25077 


0-7375 


0-84 


40 


o-433 


0-25047 


0-7274 


0-84 


5° 


0-43° 


0-25036 


0-7224 


0-84 



10 


0-505 


0-33276 


1-1312 


I-I2 


20 


0-470 


0-32685 


1-0528 


I-I2 


30 


0-458 


-32574 


1-0259 


I-I2 


4° 


0-452 


o-32537 


1-0125 


112 


5° 


0-449 


°-3^5 2 3 


1-0058 


I-I2 



IO 


0- 5 2I 


0-40923 


1-4588 


1-40 


20 


0-485 


0-40161 


I-35 8 


1-40 


30 


0-472 


0-40008 


I-32I6 


1-40 


40 


0-466 


0-39961 


1-3048 


I- 4 


5° 


0-463 


0-39942 


1-2964 


1-40 



183 



JOHN A. DAVENPORT. 



10QNCBETEJ 



As the compressive stress in the concrete at a point distant tt from the neutral axis 
is taken in (23). it will be clear that the modulus of section will be given by dividing 

(B) bv n or n'd, thus 

,,fV-, 29 m 3 r, 3 "1 14 . , 14 r, (n , 

S m = d\ - +- r-.fi -jr -, — — n — — >',({ + 7 (C) 

L3 ^100 20;/' 10 J 25 50«' 

the modulus of section per unit width. To get the total modulus of section multiply 

(C) by b, the breadth of the section. 

Expression (C) may be shortly written 

= x\i 1 -y\l-rz x (C.) 

the factors x\ y\ and z x being given in the following table for the values corresponding 
to /. y. and z given in the former table. 

Table of n' , x\ y\ and z l . 



io 
20 

30 
40 

5° 



10 

20 

30 
40 

5° 





P = ^ 






o-373 


0-25669 


0-56 


0-75067 


o-35 2 


0-26952 


0-56 


079545 


0'344 


0-27525 


0-56 


0-81395 


Q'34 1 


0-27753 


0-56 


0-82111 


o-339 


0-27910 


0-56 


0-82596 



t> = 2 



IO 


0-444 


0-39891 


I-I20 


I-26I26 


20 


0-410 


0-42012 


I-I20 


I-346I5 


30 


0-407 


0-42836 


I-I20 


1-37592 


40 


0-402 


0-43330 


I-I20 


I-39303 


50 


o-399 


o-43633 


I-I20 


I -4035 1 



P=3 



P=4 



[O 


o'5°5 




20 


0-470 




3° 


0-458 




i" 


"-15 2 




5° 


0-449 





P=5 



0-480 


0-53190 


i-68o 


1-75000 


0-449 


0-56006 


i-68o 


1-87082 


0*439 


0-57123 


i-68o 


1-91344 


0*433 


0-57847 


i-68o 


1*93995 


0-43° 


0-58224 


1 -68o 


I-9535 1 



0-65893 


2-240 


2-21782 


0-69543 


2-240 


2-38298 


0-71124 


2-240 


2-4454 1 


071985 


2-240 


2-47788 


0-72434 


2-240 


2-49510 



JO 


0-52 1 


0-78547 


2-80 


2-68724 


20 


0-485 


0-82805 


2-80 


2-88662 


JO 


0-472 


0-84764 


2- 8() 


2-()()()IO 


40 


0466 


0-85753 


2-8o 


3-00429 


5° 


0-46 | 


0-86268 


2-80 


3-02376 



184 



• , CCfMyiVUCTIONAll 
<VFJM(.INH k»lN(, ^J 



MOMENT OF INERTIA OF CONCRETE SECTIONS. 



I he values in tlif foregoinj tables have been used to calculate the moment of 
inertia and modulus of section oi square sections from expressions (J3,) and (Cj). Foi 
the purposes <i comparison the same sections are treated by the R.I.B.A. ex| 
for moment of inertia and modulus oi section. [*he results ar< iven in the following 
table along with the error in the R.I.B.A. quantities expressed as a percentage oi the 
correct value. It should be pointed out tli.it as the values of d for which //' ha been 
tabulated are 10 in., 20 in., 30 in., 40 in. and 50 in., and the cover is 2 in., the square 
sections will be 12X12 in., 22 « 22 in., 32X32 in., 42 42 in., and 52 > 52 in. Further, 
as the reinforcement will be a percentage of the area b {b 2) instead of Ir. the 
expressions (10) and (11) for the R.I.B.A. value of / and S m must be modified to— 



and 



1= l \-\-'()7r l bib-2)</ v ' 



S m =\+'UrAb-Z) d v * 



(lb) 



(2b) 



It should also be noted that d v = b— 4. that / is given in inches ', and S,„ in inches \ 



Table of Moment of Enertia and Modulus of Section. 







I. 


I. 




s HI 


s„ 




p 


b 


Inches 4 


Inches 4 


Error 


Inches' 


Inches 8 


Error 






Correct 


R.I.B.A. 





Correct 


R.I.B.A. 


° 




ll'Xii" 


932 


2,266 


+ I43-5 


25° 


378 


51-2 




22"X22" 


15,068 


29,501 


+ 92-5 


2,M3 


2,682 


+25-2 


I 


32"X32* 


76,514 


140,065 


+ 83-1 


7,416 


8,754 


+ i8-i 




4^'X-M" 


242,028 


429,122 


+ 77'3 


J 7.744 


20,434 


+ 1 5' 2 




5 2 "X 52" 


591,084 


1,028,629 


+ 74-0 


34,870 


39,563 


+ 13-5 




I2"XI2" 


1,596 


2,803 


+ 757 


35 { ) 


467 


4-30-0 




2l"X 22" 


26,906 


39,480 


+ 46-8 


3.234 


3o89 


+ II-O 


2 


^"X32" 


138,035 


192,75! 


+ 397 


11,306 


12.047 


+ 6-6 




4 2"X4-2" 


438,640 


598,937 


+ 36-6 


27,232 


28,521 


+ 47 




52^X52" 


1.073,842 


1 .447-95 7 


+ 34-8 


53.841 


55691 


+ 3-4 




I2"X 12" 


2,197 


3-34 1 


+ 52-1 


458 


557 


+ 217 




22"X22" 


37»989 


49,459 


+ 30-2 


4.230 


4,496 


+ 6-3 


3 


32"X32" 


196,206 


245.436 


+ 2yi 


14,900 


!5.34° 


+ 3-o 




42"X42" 


625,624 


768,751 


+ 22-9 


36,122 


36,607 


+ i-3 




5^x52" 


1,535.898 


1,867,285 


+ 21-6 


7L393 


71,819 


-fo-6 




I2"XI2" 


2,770 


3,878 


— 40-0 


549 


646 


+ 17-8 




22"X22" 


48,754 


59,438 


+ 21-9 


5.187 


54 3 


+ 4-2 


A 


12"X12" 


252,969 


298,121 


+ 17-9 


18,412 


18,633 


+ 1-2 




4 2"X 4 2" 


807,181 


938,566 


+ 16-3 


44.725 


44.694 


0*07 


5i"X 5 2" 


1,985,984 


2,286,613 


+ I5-I 


88,468 


87.947 


-o-6 


12" X 12" 


3,328 


4.416 


-t32-7 


639 


736 


+ 15-2 


2 2"X22" 


59.349 


69,417 


+ 17-0 


6,118 


6,311 


+ 3-i 


5 


32"X32" 


308,951 


35°- 805 


+ 13-6 


21,819 


21,925 


+ 0-5 




4 2"X42" 


988,638 


1,108,380 


+ I2-I 


53,048 


52,780 


— °'5 


5*-X 5 2* 


2.431,416 


2,705,941 


-f n-3 


104.989 


104.075 


O-q 



It may be urged that as the expressions (4,), (A.,), {Aj, (4 4 ) and (A 5 ) are not exact, 
the values of / and S,„, given in the table as correct, are not correct. But the object of 
c 185 



JOHS A. DAVES PORT. TONCBETE 



tide is 11 ts to g lcc it .:-? values of these quantities, as to point out 

the v - LI.B.A. ress as and the reasons for sach errors. Nevertheless, the 

writer ias tafc all possible care, and hopes that the va'. les given are as accurate - 

s :e-rule calcu :;ons and 01 care wiU permit: in fact, they maybe said to be 

illy " ;:::e;: For : t I iken. 

An inspection of the table sh 9 several interesting things as follows:— 

Firstly, that the error in the modulus of section is less than that in the 
moment of inertia, tor all values in the range taken, because the R.I.B.A. 

divisor, ( - ). is greaterthan the correct divisor. [n(b— 2 . 

Secondly, I lat For a r.xei percei tagc reinforcement both errors vary, 
g tting less as the section increases. 

Thirdly, that for any secti d the errors get less as the percentage rein- 
: " increases. 

irthly, that for any r.xed percentage reinforcement the errors decrease 
th the size as al e and appear, although the results do not reach it. to 
roach a lower limit which is not zero. 

Fifthly, in the higher percentages and largei - . s : ■ error in the modulus 

>f s done inges from positive to negative. 

If results o be obtained without using the moment of inertia the errors are not 

F su tgi eat impoi tanc ; but in the case of a statically, indeterminate arch, for example. 

it is i ssai I use /.and the errors, or .. xmsid ration :: them, there! re become 

import For s an example we tne elastic theory the summation 

EI El c El 

while if the principle of least work be used we have the summation 

" 2 El 

In working out thes ..-.--:- s. by a semi-graphical method, some writers recommend 

the takn g f s - For which — is constant. If 1 per cent, reinforcement be used 

th the R.I.B.A. form and the depth of the section is 22 in. or " ss, I en an error of 
out 100 per cent., or more, in /. will be communicated to — , and consequently I 

ch sen s I ns will be incorrect, possibly to a very larg I at. Further, as the error 
\.iries with tl . I error in I e - _:ions will vary with the depth, and cannot 

be rectified by a simple factor. 

F r calculating tion o: ms and cantilevers, equation (7 1 leads to an 

expre sion as follows — 

S L El 
in which c - astant which depends upon the type am and loadiiu. 11 such 

a fori sed alculath - tion or any other quantity for reinfor 

it will be - • :. from the foregoing tables oi 1 that the calculated result 
in ty easily r 100 per cent, in error if the R.I.B.A. —ion for / be used and the 

red. Results deduced from such calculated valu - 
will be largely in error and may lead to serious diminution in the actual factor s ty. 

When the usual ass .. that the compression steel lies at the c< -sure 

of the —ion is used, the expressions for / and S,„ are much simpler 

than tl 



s 






RECENT BRITISH PATENTS. 



RECENT BRITISH PATENTS 
RELATING TO CONCRETE. 

We : ..../ British Patents issued in connection 

with i ina reinforced concrete* The lust article jppejreJ in our issue of 

. ED. 



Reinforced Concrete Piles. No. 16301, [4. C. I. Deane, Walla Walla, Washing- 
ton, U.S.A. Accepted December 24/14.- Reinforced concrete piles constructed in 





Fig. 5. Reinforced Concrete Pix.es. 

accordance with this invention comprise a central metallic core (10) in the form of a 

tapered tube of suitable length, and a shell (11) of concrete, provided with an optional 

additional reinforcement (12). The head (13) 

consists of a steel ring riveted or otherwise &r<^*?. «?. 

rigidly fixed to the upper end of the core and 

having a flange (15) which gives a bottom 

ss 14). 

The bottom of the pile has a steel driving 
shoe ( [6) which has a top recess 1 17) at the centre 
of which is an upstanding threaded stud (18) 
which is screwed into the low* r end of the core 
(10). 

Eye-bolts (18 1 ) are screwed into the core 
(10) and project from the surface of the pile a 
sufficient distance to permit the attachment of 
stays and lateral bracing. The shoe may have 
a vertical aperture if the jet system of driving 
is employed. 

If a tubular core is employed, it may be 
filled with concrete after the pile has been 
driven, leaving enough of the core unfilled to 
permit the insertion of a post for the connection 
to the superstructure. 

Concrete Walls. — No. 11 no 14. G. S. Mumjord, 1328 Broadway, New York. 
I .S.A. Accepted November 26 14. — Concrete walls are constructed in accordance with 
this invention by first forming piers at intervals at the base of the wall, erecting movable 
guideways on these piers, and constructing permanent columns between some of the 
guideways; the wall is then cast progressively between the columns by moulding 
devices sliding on the guideways. 

The pi«rs (2), Fig. 1, are formed with vertical rabbets or dovetail grooves, indicated 
by dotted lines, and rise to a height of 6 or 8 ft., being placed about 20 ft. apart. A 
wooden framework or guideway (3), comprising braced beams (4, 5) bolt(d together by 
bolts (6) passing through pipe-spacers (7), is erected on each pier, the moulding devices 
(12, 13) being carried by pulley tackle from a transverse member (10), lateral bracing 
being provided if required. 

After the framework (3) has been erected, hollow-tile columns (n), which may be 
filled with cement and reinforcing rods and have metal lugs for bonding the wall fixed 
in their horizontal joints, are built between the beams (4, 5). The bracing of the latter 
i-- removed as the columns progress, the pipe-spacers 17) being allowed to remain. 

The moulding device comprises two flat members (12, 13) about 20 ft. long and 2 
to 4 ft. high, which are formed preferably of wood lined with sheet metal, and are 

c 2 1 8 7 



F g. 6. 



runforcfd concrete 
Piles. 



RECENT BRITISH PATENTS. 



[(jONCRETEJ 



braced with angle bars. Clamps (23), Fig. 5, are provided at two or more points along 
the mould to prevent bulging of the sides. 

For hollow walls a rectangular, slightly-tapered sheet-metal core (27) is supported 
by cross-bars (28) from the moulds (12, 13), and is centred by means of screws (30) 
engaging lugs (31). Additional cores may be employed for making grooves to facilitate 
the fixing of a brick facing when employed. 

To facilitate the insertion of reinforcement over openings, the columns are formed 





IZg-3. 




Figs 1, 3, 5. Concrete Walls. 

with offset portions (38) into which the down-turned ends (40) of the reinforcement 
are inserted. 

When inserting doors and windows (42), Fig. 1, the core (27) is removed and a 
brick or tile foundation is laid on the concrete; the window frame is then placed on 
this foundation and surrounded with brick (44). 

In any given position of the moulds (12, 13) the concrete is poured in, and after 
setting the mould boards are moved upwards, allowing a lap of 5 or 6 inches, and then 
clamped again in position and the operation repeated. 

Concrete Conduits, Sewers, etc.— No. 1124/14. E. R. Calthrop, Eldon Street 
House, Eldon Street, London, and F. C*. Lynde. Accepted January 14/15. In con- 
structing a conduit, sewer, etc., in accordance with this invention, a trench is first 
excavated and lined with concrete (1), Fig. 2. Suitable mould-supporting means, such 
as pipes (2), arc inserted into the concrete at appropriate distances apart, and moulds (3), 
appropriately built up of timber and lined with metal (4), are suspended by bolts (2). 

Fig. 4. 





"?ja 



w 




Fi^s. 2. 3, 4. Concrete Conduits, Sewers, etc. 

Expanded metal or other suitable reinforoemenl (<>) is then placed in position and 
held in place by the bolts (5), distance pieces (7) of concrete or other suitable material 
being advantageously employed. The space between the mould and the lined trench is 

then filled with concrete (8), and the bolts are loosened and the moulds removed when 
188 



.ItflN.M'lMRTIONAl. 
A KNQlNhl W1N(. — 



RECENT BRITISH PATENTS, 



the concrete has set, thus leaving one hall "I the conduit completed. A reinforced 
concrete covei (9), Fig. i, previous!) formed, is then cemented in position and th< 
whole is filled in with concrete (12), additional reinforcement (13) being employed il 

d 1 ' s i 1 1 1 1 • . . . 

In a modified construction, Fig. 4, a metal plate (14) ol the requisite snapi 
placed over the half conduit, these plates forming a permanenl pari oi the construction. 

j n a f ur ther modification the reinforcemenl (6) is replaced b) a speciall) wound 
rod covered with expanded metal; when the lower portion has set, the concrete covei 
(o) or plate (14) is slipped from the end into position under the spiral reinforcement. 

Concrete and Stone Buildings No. 14805/13. C. //. Provis, Mutley Rood. 
Wannamead, Plymouth. Accepted June 18 14. This invention comprises an improved 
construction of base blocks and vertical pillars for buildings formed of recessed blocks 
and pillars adapted to receive the edges of wall and floor slabs. The base blocks (b) are 
formed with recesses (b 1 ) to receive the floor slabs (a) and are provided with vertical 





Figs. 1, 4, 9. Concrete and Stone Buildings. 




Fv>v 



Fijr.<> 



holes (/)-) for the insertion of iron rods which are preferably grouted in and serve to 
support the pillar blocks. 

The pillar blocks (e) are formed with grooves (e 1 ) in their vertical edges for the 
reception of the wall slabs (d), which may be provided with grooves (d l ) to ensure a 
good joint. Vertical holes (e*) are formed through the pillar blocks in register with the 
similar holes in the base blocks. 

Vertical recesses ( c :5 ) in the pillar blocks are for the grouting of successive blocks. 

Special blocks having the features indicated above are described for corners and 
door frames. 

Hollow Concrete Walls. — No. 28799/13. W. J. Ayles, Broughton. Stockbridge, 
Hants. Accepted December 10/14. — According to this invention hollow concrete walls 
are made from slabs or by casting concrete in two independent parts, each part being 
provided with ribs disposed in two or more directions. 

When the walls are cast in situ, shuttering, comprising boards (b), Fig. 1, con- 
nected by metal plates (a), is employed. The plates have apertures (c) and bolt-slots (en), 




Fig. I. 



nf 



h. 



c m 



r" 









Fig. 2. 



=4= 



h- 



Ld-z- 



-4 



77^ 






-h 



-•—w 



\d 



is' 



d' 



Figs. 1 & 2. Hollow Concrete Walls. 



and project beyond the edges of the boards, which are provided with notches (d) for the 
passage of bolts (d 1 ). 

189 



RECENT BRITISH PATENTS. 



[QQNCBErE) 



A> , l /v<3./0. 






PI 



.c^, 



M 



p / 



9- 



^ 



j^P^H T 






z 



/ 3 



f-/ 

A 

EM 



T%i tk 



Fig. 10. 



Hollow Concrete 
Walls. 



Cores, supported as described in Specification No. 29844/12, are employed for 
shaping the interior of each part of the wall. 

At the corners, Fig. 2, angle plates {b-) 
connected to portions (b l ) hold the boards (b) 
together, inside moulding boards (bs) connected 
by plates (b^) being employed. 

For making slabs or blocks, the forms 
shown in Fig. 10 are employed. The boards 
(b) are fixed at greater distance apart and par- 
titions (/) are employed to divide the blocks, 
spacing members (h) being employed ; the par- 
titions (/) have projections (/) for positioning 
the spacing members. Cores (Z 1 ) are attached 
to one or both sides of the partitions (/). The 
mould is held firm by means of angle plates 

(/-% PY 

Reinforced Concrete Buildings. — No. 7210/14. G. B. Waite. 3 1 .s / Sired and East 
River Citv, New York, U.S.A. Accepted October 29/14.- — According to this invention 
the steel of i reinforced concrete building forms a self-supporting skeleton frame which 
is erected ahead of the concrete and gives the lines for the erection of the forms which 
are hung to and temporarily supported by the frame. 

The steel floor members are small I-beams of standard commercial shapes, capable 
of holding themselves in straight lines and stiff enough to brace the temporary structure 
and support necessary scaffolding to permit the steel construction to proceed ahead of 

^_ the concrete. The small steel floor 

t ^SS^ members are so located that they 

will act ultimately as tension 
members for the concrete, shear- 
ing strips or bars being also pre- 
ferably included; but until the 
concrete is hardened the steel 
acts independently and carries the 
temporary load. 

The columns (11), Fig. 1, 
may be a skeleton form, and are 
formed of light steel bars of com- 
mercial shapes disposed vertically, 
and preferably spaced and con- 
nected bv lattice work and a 
filling and covering of concrete, 
or they may be formed of steel 
members connected together, as 
shown at (14), and enclosed in 
concrete, or of other suitable 
form. 

Light steel I-beam girders 
(18, 19) of single or twin forma- 
tion respectively extending be- 
tween and supported by the 
columns and steel cross-beams 
(20) are disposed transversely of 
and supported On the girders ( i.X). 
The light steel girders and floor 
beams constitute in the finished 
structure the steel reinforcement 
of the finished concrete beams. 
The steel floor members need be 
nl sufficient iveighl and strength onlv to tie the light frame structure together and hold 
up scaffolding and other normal and temporary building loads. 

190 




Fin. )■ Reinforced Concrete Buildings. 



{ t, CON> IVUC-riONAH 
1 «VKN(.1NKKW1N<. ^J 



RECENT BRITISH PATENTS. 



When flu built-up steel columns, such ;i^ shown al i) in Fig. i, arc used, the 
girders are connected t « > brackets supported l>\ the columns substantia!!) as shown in 
fig. .;. and the columns and girders and flooi beams are then encased in concrete and 
sei ve as i einfoi cements thei efoi . 

I ch girdei and floor beam, various l< »j ms ol \\ hii li are described, carries upward 
extending U-shaped sheai bars (30) which extend neai to the surface oi the concrete 
floo 

In the construction shown in Fig. io, lour angle bars (35) are employed, each 
Forming one corner of the rectangular column structure. These bars are connected 
together al their ends by means of clamps (36), and somewhat below the floor level .'111(1 
approximately on the ceiling level anchoring (lamps (37) .ire secured to the angle irons 
ol the columns forming temporary supports for the floor structure. 

Bars (39) carried by the clamps form supports for the floor beams (41), which 



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i 


1 


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37 
3$~ 


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1^ 



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■42 -?/ 



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Figs. 3 & 10. Reinforced Concrete Buildings. 



extend within the column any suitable distance, and for that reason need not In- 
accurately cut to proper lengths. These floor beams are preferably made up of two 
channel iron members separated a suitable distance from each other for the great< c 
portion of their length, these separated members being curved inwardly or converging 
towards their ends, so that their ends within the column frames are closer together, 
these bars being held by separators at the requisite distance apart. 

Short beams (43) are provided to take up the negative bending movement over the 
points of support for the floor beams, and bars (44) connect the upper and main rein- 
forcements. 

To take up the shear stresses, shear bars (46) are bent around the floor beams (41) 
and are carried to a point slightly above the reinforcing beams (43) ; these shear bars 
adjacent the columns embrace the reinforcing beams. 

Concrete Reinforcements No. 30 14. F. A. Macdonald and Partners, 135, Wel- 
lington Street, Glasgow. Accepted November 5/14. — This invention relates to steel rods 
or bars for use in reinforced concrete work of the type in which a series of uniformly 
arranged circumferential or like projections are provided to ensure accurate spacing of 
the auxiliary reinforcements along the length of the bar and to provide a mechanical 
bond of the main bar with the concrete. According to the present invention the pro- 
jections take the form of twin projections or ridges having the intervening space or 
groove adapted to exactly fit the auxiliary reinforcement, so that slipping in either 
direction is prevented. The invention also provides improved rigid seat plates or spacers 
for spacing apart reinforcing rods, and for affording connections for shafting brackets 
and similar attachments to concrete beams and other members. 

The continuous bar (a) has raised twin circumferential projections or ridges (b, b 1 ), 
which are spaced at regular intervals along the length of this bar, these projections 
being formed during the rolling of the bar. 

The twin circumferential projections form a series of abutments, usually 3 in. 
apart, along the full length of the bar with a locking space (c) between them, in which 
space auxiliary reinforcements required for diagonal tension in reinforced concrete 
beams and for compression stresses in reinforced concrete columns and piles are placed, 
and the twin projections (b, b 1 ) securely lock the auxiliary reinforcements against 
longitudinal slip along the main central bar. 

Fig. 3 shows a modification in the form of helical twin projections or ridges (b 2 ). 

191 



RECEST BRITISH PATEXTS. 



CONCEPT] 



£. 6 shows the use of the bars with diagonal shear members of variable spacing, 

but helical bars may be employed. 

The lock sj • , Fig. 8, is adapted to take six rods or bars (a) in two horizontal 

s of three bars in each tier in the lower part of the pari metallic truss. These lock 

spac- - :nade with spaces in the form of three internal triangles, the centre triangle 




F G - 



-• 5 



P'G 6 






nc a 




= o 9 
Fig~. J, 5. 6. S. 9 and 14. Cohcbeib Reinforcements. 

*>eing formed in inverse position to that on either side of it, and each angle of the 
triangle is rounded to such radius as is required to receive the bar (a) of the truss. 

< ' n the rods or bars (a) and lock spacer (s) being adjusted to their correct positions, 
as shown at Fig. 12, a lever [d] of the form shown at Fig. 9 is inserted between the 
upper and lower tiers of bars (a), and by turning the lever and inserting two or more 
kev pieces (h) the various bars (a) forming the part metallic truss are locked into 
position. 

A modified form of spacer is shown in Fig. 14. The two inner bars of the lower 
tier are first placed in the positions shown, and a horizontal key (/?) (a short length of 
round iron of the exact requisite diameter and length) is then superimposed on these 
bars, and is then placed in position, and a temporary vertical key (e) (of wood or other 
suitable material) may then be arranged to hold the vertical tiers of bars apart from 
each other. 

The two outer bars of the lower tier are 
then placed within the curved ends of the 
- . nd the two outer bars of the upper 
;re placed in position. The binder- 
(made from stout annealed wire or other suit- 
able material) are then placed in position 
along the length of the lower part of the truss 
as required, and the temporary key (c) is 
-after withdrawn. 

This - r (r) enables the whole of the 

supported by means of the 
provided by the horizontal key (fe), 
tlv- e-nds of whi< h an- supported on certain 
of the bar- (a), which bar- are again sup- 
ported on th<- curved end- (r 1 ) of the spacer, 
which owing to it- form also - - to hold 

the bar- apart from <;u h other, and on th' 
bind eing placed in position a tru-- 

containing eight bar- i> formed by means of 
the -pacer, in which the- bar- arc- rigidly 
hc-ld apart from each other in the- lower area 
ctf the beam, and which can be handled and 
transported without difficulty or distortion of 
the component members. 

For attaching -hafting brackets .and other connections to reinforced concrete beams 
192 




I :- 



FIG Z& 



Concrete Reinforcev: 



rj.CONM'UlKTIONAli 

[A 1 MilM \ I'lNt. —J 



RECENT BRITISH PATENTS, 



in combination with trusses formed b) means -.1 the spacers, a channel (w) (Ftg. 28 
formed from sheel metal is provided, with holes in the sides opposite to each othei nl 
such intervals as are required, and the channel is Hun secured to the trusses b) keys (x) 
oassed through these holes and between the uppei and lower tiers o\ bars (a) of the 
trusses and t» this means loads may be suspended from the beam ... an) position 
reouired as the channel is efficient!) secured and attached b) the steel keys (*) to the 
steel reinforcemenl of the reinforced concrete beam. Movable screwed studs (y) ma) be 
p] iced within the channel (w) to an) number and in any position required, forming the 
means of movable attachment for shafting brackets and other connections. 



>93 



A. F. DYER. 



[CONCRETE] 







HALIFAX OCEAN 

TERMINALS. 
NEW PIER No. 2. 

INTERCOLONIAL RAILWAY OF 

CANADA DEEP-WATER TERMINALS, 

HALIFAX, N.S. 



By A. F. DYER, A.M.Inst.CE. 

The following particulars regarding the construction of the New Pier at Halifax are 
specially interesting on account of the "very large piles driven. — ED. 



Towards the end of 1910 the Department of Railways and Canals of Canada 
decided to enlarge and improve the shipping- terminals of the Intercolonial 
Railway at Halifax, N.S., in order that the rapidly increasing' transatlantic 
shipping - making use of that port mig"ht be conveniently accommodated. 

The shipping piers then owned by the railway at their 4 deep-water ' 
terminals consisted of a flour-loading pier, 470 ft. long by 50 ft. wide, which 
had been built by Sir Samuel Cunard before he left Halifax to found the 
Cunard Shipping Company; old Pier No. 2, 560 ft. long by 65 ft. wide, having 
a two-storey wooden shed, and used by incoming passenger and mail steamers; 
Pier \o. 3, ojo ft. long by 165 ft. wide, with a one-storey freight shed, used 
by incoming" freight and outgoing passenger and freight steamers; and Piers 
4 and 5, used for the shipping of coal and lumber. All these piers being 
supported on timber piles, and having wooden floors, require a considerable 
outlay for maintenance, for although the Teredo is practically unknown in 
Halifax Harbour, the Limnoria is very active. 

In the spring of 191 1 the following scheme of development was put 
forward by Mr. J. Kennedy, Consulting Engineer to the Montreal Harbour 
Commissioners, and approved of by the Department of Railways and Canals : 
A new pier, 800 ft. long by 235 ft. wide, to be built on the old Cunard property 
in place of the Cunard Pier, old Pier No. 2, and the Immigration Building, 
all threi of which were to be demolished, the last two on the completion of 
the new pier, which would then be known as New Pier No. 2; Pier No. 3 was 
to be lengthened to 800 ft. and widened southwards to a width of 235 ft., 
leaving a dork- 380 it. wide between its south side and the north side of New 
Pier 2 ; a new pier, No. 4, 800 ft. long by 235 ft. wide, to take the place of 



existing Piers 4 and 



h a basin 275 ft. wide on the north of Pier 3; and 



a fourth pier, 700 ft. by 195 ft., 250 ft. north of Pier No. 4. This scheme 
provided lor about 6,000 lineal It. of berths for ocean-going steamers, against 
the 3,320 ft. tin n existing. 

It was derided to start work with the building of New Pier No. 2, as the 

construction oi this pier would least interfere with the existing accommodation. 
In designing the new piers, the two considerations of economy of con- 

'9+ 



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REINFORCED CONCRETE PIER, CANADA 




l 9S 



A. F. DYER. iCQNCREXE.1 

struction and permanency <>t the structure determined the type to be used, 
which is that ot a reinforced concrete floor supported on reinforced concrete 
piles. This type of construction was well suited to the local conditions of the 
site, where the depth of rock-bottom varied from 42 ft. to 68 It. below low- 
water level of spring- tides, which necessitated a substructure below the pier 
floor of from 61 ft. to 87 ft. in height. 

Borings taken over the site of the new pier indicated that a layer of hard 
clay or hard pan covered the rock to a depth which varied from 2 ft. to 12 ft. 
Above the hard pan there was found a layer of soft mud, which had a depth 
of nearly 30 ft. at the shore end, but ran out to about 5 ft. at the outer end 

of the proposed pier. 

NEW PIER No. 2. 

The elevation of the pier deck was determined by the existing" tracks in 
the railway yard, and on the other piers at 19 ft. 2 ins. above extreme low- 
water level of spring' tides, which is 3 ft. 6 ins. above top of rail. Owing to 
the small height of the structure above low water compared with the depth 
of the foundations below low water, a system of diagonal transverse bracing- 
would not have greatly increased the stability of the pier and its ability to 
withstand the shock of a large vessel striking it on one of its sides, and 
therefore recourse was had to the use of reinforced concrete brace piles driven 
at an angie of one-in-three to the vertical and having their heads consolidated 
with the transverse girders of the pier floor. It is believed that this is the 
first instance of such a system of bracing- being used for a reinforced concrete 
pile pier. Further stiffening- of the structure was obtained by forming a bank 
of dredged material under the outer end of the pier where the depth of water 
was greatest and the thickness of the material overlying the rock was least. 

The question of the durability of reinforced concrete piles immersed in 
sea water, in a climate such as prevails during the winter months in Halifax, 
had now to be dealt with. The large ratio between the surface exposed and 
the bulk of the concrete in this type of construction is one of its weak points, 
and special measures had to be taken to prevent any deteriorating action of 
the water on the concrete. 

'1 lie measures taken to prevent as far as possible any injurious actions 
taking plaee on the concrete piles were :— 

The Portland cement used for the making of all concrete below high-water 
level did not contain more than 6"3 per cent, of alumina. 

All concrete below high-water level was mixed in the proportions of 1 part 
cement, \\ parts sand, and 3 parts crushed quartzite gravel, with the object 
of obtaining a rich and as dense and non-porous a concrete as was possible. 

All concrete surfaces from low-water lev-el to about 2 ft. above high water 
wen- sheathed with two layers of 2 ins. creosoted pine planking bedded on 
cement mortar. The inner surfaces ol the planks were coated with pitch to 
prevent any deteriorating action taking place between the creosote in the wood 
and the concrete ol the piles. This sheathing keeps the concrete surfaces 
moist, prevents all frosl action, and protects the concrete from abrasion by 
ice as well as the wearing action ol the wash of the water. 

The plans included the erection of a Iwo-storev freighl shed 200 ft. wide 

19') 



[j T cTONynaicTioNAtJ 
[a BMM MEM I Eg '» g | 



REINFORCED CONCRETE PIER, CAS ADA. 



.ind extending from the bulkhead line i<> within [5 It. of the outer end of 
the pier, I his shed allows room to run .1 railwaj track along each edge of 
the pier. I wo additional r;iil\\;i\ tracks run the whole length of the shed 
down the centre ol the pier, dividing the lower floor into two separate freight 
doors each 88 ft. in width. I he columns supporting the shed are spaced 
39 It. 6 ins. transversel) and 18 ft. longitudinally, the long transverse span 
being decided upon in order to facilitate the handling of gangfways. 

I he loads for which the pier and shed floors an designed are: Pier deck, 
[,000 11). per sq. It. live load; track girders, 4,500 lb. per running foot of each 
rail live lead; upper floor ol shed, 500 lb. per sq. It. live load; and roof, 
1 10 lb. per sq. It. total load. 

The longitudinal spacing of the shed columns determined the distance 




Fig. 2. View of Shed Forms. 
Ocean Terminals, Halifax, Nova Scotia. 

between each bent of piles, and it was decided to use piles capable of supporting 
a load of at least 100 tons, including their own weight in water. This neces- 
sitated the use of piles 24 ins. square in section, and required thirty-three 
vertical piles and six sloping piles in each bent. Two vertical piles and one 
sloping pile are driven beneath each side column of the shed, three vertical 
piles and one sloping pile beneath each interior column, and the remainder of 
the vertical piles are spaced out between the column groups at approximately 
10 ft. centres. Of the six bracing piles three are driven with heads inclined 
to the north side of the pier and three to the south. 

The amount of reinforcement in the piles varied in accordance with the 
length of the pile as cast, and was fixed by the amount required for their safe 

197 



A. F. DYER. 



ICQNCBETEJ 



handling when being placed in position for driving. No metal shoes were 
used. Some additional stirrups were placed near the head of the piles to 
prevent excessive breakage while driving, and the longitudinal rods were 
allowed to project 3 ft. beyond the concrete to save the labour of cutting 
away the concrete iri order to secure the necessary bond of the pile reinforce- 
ment with the concrete of the pier deck. In order to minimise the bending 
moments in the piles during handling, it was specified that all piles were to 
be lilted in such a way that they were suspended at pcints one-fifth of their 
length from each end while in a horizontal position. By the observance of 
the above rule the cracking of the piles while being conveyed from the moulding 
yard to their ultimate position read}' for driving was entirely eliminated. 




Fi^. 3. Pile Driver. 
Ocean Terminals, Halifax, Nova Scotia. 



The piles to be driven as brace piles were reinforced in a similar manner 
to the vertical piles, but were cast with a camber, so that when built into the 
pier and under an axial load ol So tons, the stresses on the cross-SCCtion ol the 

concrete, due to this load, and the bending moment of its own weight would 

be uniform. The number of concrete piles used in the work is 1,801, 238 of 

which were driven at an angle as bracing piles. 

'I he pier deck is built entirely of reinforced concrete, carried on reinforced 

Concrete girders 36 ins. deep, which run transversely across the pier along 
the pile bents, and on girders of the same depth running longitudinally at an 
average of 9 ft. 10! ins. centres. The 18 ft, by Q ft. io! ins. rectangle thus 

198 



\j T CON.vriMKTIONAlJ 
Kv hN(.lNhb.WlN(. — , 



REINFORCED CONCRETE PIER, CANADA. 



formed is divided again b) a transverse floor beam 24 ins. deep. The slab 
is s ms. thick, reinforced in both directions with !-in. round rods al 7-in. 
centres, even alternate rod being bcnl up over the supporting beam. 

All he. mis ;ni(l girders are designed as T-scction beams, sufficient web 




reinforcement being- used to take care of the excessive shearing- stresses, the 
top ends of the U-stirrups being bent horizontally and carried into the slab 
as far as the table of the T extends, in order that the shearing stresses 
occurring between the web and table be properly cared for. 

199 



A. F. DYER. 



i^CBEXFJ 



Owing to the side and central railway tracks being- carried at a level 
3 ft. 6 ins. below that of the pier deck proper, transverse concrete gussets 
were built in at the four breaks in the floor level, in order that the rigidity 

of the floor system 
w o Li 1 d be main- 
tained from o n e 
sick- of the pier to 
the other, and the 
whole floor would 
act as a monolith 
in resisting t h e 
shocks of larg-e 
vessels. 

A concrete 
beam 51 ins. deep 
is carried along 
each edge of the 
pier, and to the 
outside of this is 
secured a rubbing 
o z lender of pitch 
pine with a vertical 
face of 20 ins. At 
the outer corners 
of the pier the 
depth of the fender 
beam was increased 
to about 11 ft., the 
corners being cut 
diagonally across, 
leaving a flat con- 
crete surface lO ft. 
wide by 11 ft. deep, 
strongly braced at 
the back by gussets 
from the pier floor. 
Numerous holes 
were left in this 
concrete face for 
attaching thereto 
fenders made up of 
birch or willow 
s a p 1 3 ngs bound 
together into bundles. Two layers of bundles are attached to each corner, 
the larger ones towards the middle so as to form a rounded fender, the whole 

being- bound in secuiely with three sets of steel cables. 

Cast iron mooring posts of the mushroom-head type are placed at 54 ft. 
200 




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REINFORCED CONCRETE PIER. CANADA 



centres along each side and outei end oJ the pier. Each |x»st is anchored 
down with eight i A-in. round holts, 30 ins. long", built into the concrete deck. 

The interior columns supporting the uppei floor of iln shed ai<' circular 
in cross-section, 25^ ins. in diameter, reinforced with i!-in. vertical rods and 
J -in. hooping at [-in, pitch. The side columns are rectangular in section, 
[6 ins. by 20 ins., reinforced with vertical rods with J-in. lacing at 6-in. centres. 

The upper floor be. mi system consists ol transverse girders supported on 
the six columns ol each bent, and longitudinal beams at <) It. [oJ in. centres 
carrying a concrete slab 7 ins. in thickness. The transverse girders have a 
span ol 39 It. 6 ins. centre to centre ol columns. In order to reduce the 
height of the upper 
floor above the pie r 

deek to .i minimum, ^jflk 

and at the same 
t i m e to ha v e 
adequate headroom 
for t h e 1 o w e r 
storey, the depth 
of the girders was 
made 30 ins. and 
the thickness of the 
floor slab was in- 
creased to 9 ins. 
for a strip of 18 
ins. along each side 
of the girder to 
provide sufficient 
compression area. 

The roof con- 
sists of tar and 
gravel roofing- laid 
on boarding- and 
carried on a light 
reinforced concrete 
slab. The roof 
beam system con- 
sists of 12 in. by 
42 in. transverse 
girders carried on 

12 in. by 12 in. concrete posts, and 8 in. by 12 in. longitudinal beams, 
with spans the same as the upper floor. The centre bay of the roof is raised 
5 ft. for the total length of the building, thus forming a clerestorv and pro- 
viding good light for the upper storey. 

Steel sliding doors enclose each side of the lower storev, except for a 
length of 72 ft. at the shore end, which is given over to shipping and railway 
offices. On the upper floor a 17-ft. wide opening, closed with two steel 




6. Brace Pile ready for lowering into position. 



20I 



A. F. DYER. 



TOCRETFJ 




• 1 wl 




202 



,"5, oonstimicticwa'iI 

lA KNCilNKI KINC. — -J 



REINFORCED CONCRETE PIER, CANADA, 



sliding (loots, is provided .it 36 ft. centres. All sliding doors for both floors 
are provided with windows glazed with ribbed-wire u: loss. 

In ordei to secure additional yard room al the base ol the pier, the o!d 
bulkhead of the Cunard pier had to be abandoned and a new bulkhead built. 
This iu w bulkhead was IhhIi 250 ft. east ol the easl side ol Water Street, 
.nid was formed of timber cribwork filled with rock and sand. Alter the 
commencement of tin work il was decided to further widen the yard, and an 
additional to6 It. of yard room w;is obtained by the construction ol a reinforced 
concrete pile wharf similar in construction to the pier deck. The length ol 
the pier was thus reduced to 694 ft, from the new bulkhead line. 

Construction Work. The contract for the construction of the pier and 
shed was let to the Nova Scotia Construction Company, Ltd., of Sydney, CD., 
in September, [911. Work was immediately started on the clearing of the 





Fig. 8. Interior of Shed. 
Ocean Terminals, Halifax, Nova Scotia 



site and the removal of the old piers, which turned out to be a somewhat 
tedious work on account of the large number of short stumps of piles which 
had to be removed by the help of a diver. Meantime the contractors had been 
preparing their pile-making- yard. 

The moulding yard measured 800 ft. by 600 ft. wide. A gravel excavating, 
crushing, and concrete-mixing tower was erected at the east end of the yard, 
mounted on wheels which ran on tracks across the whole width of the yard. 
Parallel tracks were laid across the west end of the yard, on which an anchor 
tower, similarly mounted on wheels, was placed, and a cable way stretched 
between the two for the conveying of the concrete to the pile moulds. 

On top of the main tower, 80 ft. above track level, was placed a winding 
winch operating a drag-line excavating bucket. This bucket emptied its 

contents of sand and gravel into a hopper over a grizzly, all stones not passing 



n 2 



20 l 



A. F. DYER. 



[OTCBETE] 



through being conveyed to a jaw crusher. The material is then passed over 
J-in. and i-in. screens to separate the sand from the stone, any stones not 
passing' through the i-in. screen being elevated to a second crusher. 

Chutes from the stone and sand bins led the materials to the mixer plat- 
form, where they were measured before passing into the mixer. The concrete 
mixer was a one-yard cylindrical revolving mixer, which discharged each batch 
into a bottom dumping bucket which travelled along the aerial ropeway to 
the pile moulds. 

Once the concreting of a pair of piles was commenced, no stop was allowed 
before they were completed, so that all joints in the concrete were eliminated. 
The maximum amount of concrete poured in a day of ten hours was 168 cu. yds. 

Owing to the weight of the concrete piles, the smallest of which weighed 
12 tons and the largest 46,000 lb., the conveying of them to the site of the 
work presented certain difficulties for which special arrangements had to be 
made. In order that the piles could be placed accurately in the positions 




Fig. 9. North Side of Pier. 
Ocean Terminals, Halieax, Nova Scotia. 

required by the plans, pile leads were hung on a carriage travelling on rollers, 
which gave it a forward movement of 7 ft., while the leads themselves can 
be traversed across the face of the carriage 4 ft. on each side of the centre line. 

The pile leads, which are built in the form of a three-sided box girder, 
arc 75 ft. in length and weigh about 72,000 lb. Over pulleys on top of the 
leads pass the cables for handling the piles, the pile guiding-fingers, and the 
pile hammer. The hammer runs in guides on each side of the leads, which are 
designed with a switch at the top, so that the hammer can be run into the 
leads, thus allowing the pile to hang vertically in front. 

In order thai the brace piles could be driven, the leads are pivoted at 
the centre of their length, and their lower ends can be carried over S ft. to 

either side of the centre by operating a long threaded horizontal shaft, thus 

allowing the leads to be canted at the angle required for these piles. 

The method followed in placing and driving a pile was as follows : A pile- 
204 



^'{SEStKl'SSlil REINFORCED CONCRETE PIER, CANADA 



drivei mow whs fiirsi placed in position bj means ol cross ranges, and anchored 
1»\ lowering her spuds. Straps were placed around the pile to be driven as 
it Li\ on the deck ol the scow on which it had been brought up from the yard, 
and the pile lifted horizontal!) 1>\ one ol the forward derricks and swung 
round in fronl ol the driver so that the head <>l the pile came in front oi the 
pile leads. Hie swinging ol the pile was accomplished by manipulating the 
forward spuds of the pile-driver scow. The pile fall, having been made fasl 
to the staple projecting out <>f the brad <>l the pile, was hoisted up, and at 
the same time the derrick fall was lowered and the pile gradually raised into 
a vertical position, the straps around the pile being taken oil as the strain 
came off them. The pile leads were then moved as required for the exact 
centering of the pile. On the pile being lowered it penetrated the overlying 
soft mud with its own weight. This mud was found to have sufficient stiffness 
i > hold the pile vertically when its depth was about equal to one-third of the 
length of the pile; as a general rule, however, the piles had to be stayed while 
the hammer was being adjusted on their heads. 

The amount of hammering which the piles required to drive them to 
refusal varied a great deal. In some places, where the depth of the hardpan 
was small, the pile would come to a stop after 200 to 300 blows, while in 
other places they would require nearly 1,800 blows to drive them to rock. 
The rate of penetration through the hardpan was small, the last foot or so in 
many cases being - penetrated at not more than one-thirtieth of an inch per stroke. 

When no machine troubles were met with, an average of ten piles could 
be set and driven in ten hours. In some weeks, however, the average would 
slightly exceed twelve per day, and the best day's work was eighteen. 

In order to test the bearing power of the piles after driving-, load tests 
were made with a floating' load of 180,000 lb. on certain piles. The load, 
which consisted of two scows of 90,000 lb. weight each, was attached to the 
ends of a steel girder resting - on the head of the pile and made fast at high 
tide, the pile and load being- securely braced to prevent swaying - of the pile 
when under load. On the tide falling - , the whole load was carried by the 
pile. Tests were made on piles which had been driven to different degrees 
of penetration, with the following results : — - 

Pile going - i-ioth of an inch per blow, settlement under load i-i5th in. 

»> >> I- 5^ n >> >> " n >> I-20th ,, 

,, driven to refusal, ,, ,, ,, nil. 

The problem of building forms of the necessary strength and stiffness on 
the short length of pile projecting above the water was not an easy one, but 
was successfully solved by the contractors. 

The concrete used in the construction of the pier deck and shed was 
mixed in the proportion of 1 part Portland cement, 2 parts sand, and 4 parts 
1 -in. crushed gravel. Batch mixers were used throughout, and the concrete 
was distributed from an elevator tower by chutes. Special care was taken 
to properly imbed all reinforcing steel, concrete made from a finer crushed 
stone being used where found necessary. 

The surfaces of the floors were finished with a finishing coal of 1 to 2 

20s 



.4. F. DYER. [QQNCEEXEi 

coarse mortar trowelled lo a fairly rough surface. The lower Moors were built 
with a fall towards the railway tracks of 4 ins. in 45 ft. 

By the middle of December, 1913, the piles had been driven and the pier 
floor completed to within 115 ft. of the outer end, at which place the work 
was suspended until the following' spring', and the portion of the pier built 
was equipped with temporary wooden freight sheds and used throughout the 
winter by freight steamers. During" this time the ability ;>f the pier to with- 
stand lateral blows from larg'e vessels was demonstrated on more than one 
occasion. 

The whole of the concrete work completed by December, 1914, and the 
lower storey of the shed, is now in full use. The upper storey is at present 
being" fitted up for the temporary examination of immigrants, and was expected 
to be ready for use in March of this year. 

The contract for the construction of the pier and shed has been carried 
out by the Nova Scotia Construction Company, under the management of 
Mr. Hamilton Lindsay, assisted by Mr. J. Shepherd Lee, B.Sc. Mr. John 
Kennedy, M.I.C.E., is Consulting- Engineer for the Dominion Government 
for the work, and was assisted in the desig"n by the writer and by Mr. R. A. 
Lockerby, B.Sc. The cost of the work, complete, will be about $1,125,000.00. 



:06 



Ta r CON>TPUCTIONAl.l 
t/V I JsKiUMKl -KINO — J 



ECONOMY IN REINFORCED CONCRETE. 




It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. ED. 



THE CONCRETE INSTITUTE. 

ECONOMY IN REINFORCED CONCRETE 
CONSTRUCTION, 

By T. A. WATSON, A.M.Inst.C.E. 

The following is an abstract from a Paper read at the Fifty-seventh Ordinary General 
Meeting of the Concrete Institute. .1 short summary of the discussion which followed 
is also given. 

You will notice that the Paper is supposed to be on " Economy in Reinforced Concrete," 
which would leave the broader aspect of the economy of reinforced concrete untouched, 
and would confine the discussion within limits which I did not intend; so with your 
permission I shall touch on points in the larger sphere, though I may be attempting 
to make you acquainted with things which you already know. 

As you are aware, the London County Council have framed a set of regulations 
dealing with the construction of buildings entirely in reinforced concrete, specially with 
a view to the construction of buildings with their external walls of the material, it being 
supposed that a great economy in building construction would thereby result. I regret 
to say, however, I have not found that this result has been achieved. 

After the new General Post Office had been constructed and Sir Henry Tanner had 
read a paper on it at the Royal Institute of British Architects, the view was expressed 
by many architects that a new era had arrived in construction ; and so it had, in a way, 
but not, I think, in the way that most of them seemed to believe. 

It was quite true that by adopting reinforced concrete for the General Post Office 
Sir Henry Tanner had saved a vast amount of public money, some ^76o,ooo in actual 
construction cost and some ,£50,000 additional for the value of extra floor space obtained 
by thin walls, and it was an achievement of which anyone might well be proud; but 
perhaps the chief value of this building to posterity was the way in which it showed 
that reinforced concrete could be used more economically still. 

We are shortly to have regulations allowing us to build external walls in reinforced 
concrete. Things have progressed slightly in recent years, and a reinforced concrete 
framed building with q-in. or even 14-in. external panel brick walls is even more 
economical than the original conception of reinforced concrete external walls. 

In a way this is disappointing, because it destroys an outlet for the genius of the 
architect to incorporate in his design the expression of the method of construction in 
reinforced concrete, leaving him only a skeleton to clothe in brick, stone, marble, tile, 
or other building material, but to my way of thinking it is true economy. 

There is, however, another aspect of walls which I should like to touch on, and 
that is retaining walls, and particularly retaining walls outside a building. Till quite 
recently these were built either as gravity retaining walls of sufficient weight and 
stability in themselves to sustain the earth pressure and superimposed load from pave- 
ment and roadway, in which case they were enormously thick at the base, one 20 ft. 

207 



THE CONCRETE INSTITUTE. [CQNCBEfB 

high requiring to be about 7 ft. thick, or they were built as a series of vertical arches 
supported by walls at right angles to them and forming a series of dark dismal vaults. 

In both cases the outside of these walls next the earth was lined with asphalt 
or a vertical damp course of some kind. At the present time reinforced concrete walls 
are being constructed in many cases without a vertical damp course, which even in 
damp ground is unnecessary. In passing let me say, however, that in waterlogged 
strata I personally am of opinion that a vertical damp course is absolutely necessary 
even with reinforced concrete walls. 

But to compare prices and to give gravity walls the best possible chance let us put 
the average thickness of a wall 20 ft. high at 5 ft. 3 in. thick. In a wall of this thick- 
ness there are per yard super- — 

672 bricks at 34s. per 1,000 

Extra over 48 bricks for facing at 5s. per 1,000 

iV-yard cement mortar, 1:3 

Labour laying 

Pointing one side only 

Total 43 7 

Leaving out the vertical damp course, a reinforced concrete wall, including all 
counterforts and without any horizontal struts to the main building, can be built for 
32s. per yard super. The price is made up as follows : — 

Per foot-run of wall. 
s. d. 
Cub. ft. of concrete 27*3, at is. id. ... ... 29 7 

Lb. of steel 105, at i^d. ... ... ... ... 13 1 

Centering no ft. super, at 3d. ... ... ... 27 6 



s. 


d. 


22 


10 


O 


3 


8 


9 


10 


6 


1 


3 



70 2 for 2^ yds. super, 
or 32s. per yard super. 

After the enormous saving shown above the saving on a reservoir wall seems a 
mere trifle, but still it is worth having, and it is enhanced by the fact that it is 
unnecessary to have an asphalt lining on the inside of a reinforced concrete reservoir, 
as it is not impossible to make a reservoir watertight enough for all practical purposes 
without this lining. So that even if there were no saving m the cost of reinforced 
concrete walls against brick for a reservoir, yet there is a saving of 5s. to 6s. per yard 
super on the lining. 

Economy of Pillars. — Take a pillar carrying, say, 200 tons central load, height 
16 ft. from floor to floor, ends fixed. A steel stanchion 40 sq. in. in section, weighing 
136 lb. per foot-run exclusive of cap base and connections of girders, is required, size 
14 in. by 16 in. According to the 1909 Act relating to steel-framed structures this has 
to be surrounded by 2 in. of concrete (making a total of 18 in. by 20 in.), which latter, 
to prevent its cracking, has to be reinforced with rabbit wire-netting, or spiral binding 
of some kind, the total cost of which figures out something like the following : — 

£ s. d. 

Steel stanchion, 16 ft., at 136 lb.; 2,176 at ^13 per ton erected... 13 o o 

Concrete surrounding same, 23 cub. ft. at 8d.... ... ... ... o 15 4 

Rabbit wire, So ft. super at VI. ... ... ... ... ... ... 034 

Centering, 144 ft. super at 3d. ... ... ... ... ... ... 1 16 o 



£*S H « 



In order to make a saving on this price, and to conform with the regulations 
proposed, it is necessary to have a column slightly larger in section than the steel one. 
Suppose, for convenience, we say 24 in. by 24 in. 

Allowing a stress of 600 lb. per sq. in. in concrete and 16,000 lb. per sq. in. in steel, 
the amount of steel required in a column this size is S3 lb. per foot-run including 
links, binding, etc 



208 



^SnimT C J'i!S^ ECONOMY IN REINFORCED CONCRETE 



llenms. II we take beams, saj one oi 25-ft. span oi a series al 20 ft. centres, load 
cwt. per sq. ft. of floor, including weigh! »>f floor. A steel girdei consisting of, 
say, one 14 in, l>v 6 in. and four to in. by ', in. plates, top and bottom, weight \<>(> lb. 
per foot-run, is required. This, when covered with the requisite amount "I concrete, 
gives a depth of beam below floor level of 22 in. and a width * > f 14 in.; and for ih<- 
sake of making as mar a comparison as possible, lake a reinforced com rete beam 
of the same depth from floor to soffit of beam. A beam ol this depth allowing 600 lb. 
proposed stress in concrete and 1 6,000 lb. stress in steel requires no lb. of steel re- 
inforcement per foot-run, making allowance for lappage of bars and shear members, 
and as regards weight Of steel this compares very favourably with the steel girders. 

Floors. — To fill in the floor space 25 ft. by jo ft., most architects nowadays would 
probably use some kind of hollow tile reinforced concrete floor, and I am of opinion they 
would be right ; but on the other hand there are some who would use R.S.J, fillers, and 
the most economical way would then be to divide the 25 ft. up into three bays with two 
R.S.J. [5-in. by 6-in. at 8-ft. 4-in. centres and use 5-in. by 3-in. by 11-lb. R.S.J, fillers 
at 3-ft. centres from 1 5-in . by 6-in. joist to 15-in. by 6-in. R.S.J., and a thickness of 
floor of 7 in. Comparable with this would be a reinforced concrete slab 5A in. thick 
supported by secondary beams at same centres as the 15-in. by 6-in. R.S.J, and supported 
by the main beams as above. Reinforcement required in 5^-in. slab amounts to 15 lb. 
per yard super. 

Now, working out the cost in the two cases in a piece of floor 25 ft. by 20 ft., we 
have for the steel-framed structure £j$ 14s. 3d., as against ^"59 14s. 3d. for the 
reinforced concrete structure,* saving, say, ;£i6 on a piece of floor 25 ft. by 20 ft., or 
a saving of 10 to 20 per cent, by constructing in reinforced concrete instead of in steel. 

Bridges, etc. — It seems hardly necessary to mention that in the construction of 

bridges, say up to 300ft. span at least, reinforced concrete is nearly always the most 
suitable material. There are, of course, exceptions, but the mere question of the cost 
of maintenance of a steel bridge seems enough to condemn it, whilst a great argument 
in favour of the reinforced concrete bridge is that it requires no maintenance and 
becomes stronger as it grows older. 

Apart, however, from the question of maintenance, the saving effected in cost of 
construction of bridges in reinforced concrete over steel bridges is sufficient to justify 
its adoption, as much as 40 per cent, having been obtained in a bridge of 42 ft. span 
by 26 ft. wide between parapets. 

The question of maintenance is also enough to decide an architect or engineer to 
choose reinforced concrete for the construction of, say, small water towers, coal bunkers, 
gasometer tanks, or any similar structure heretofore built in steel and exposed to 
atmospheric conditions, even if reinforced concrete is not cheaper in the first instance. 

With regard to timber structures the same applies, and in addition the relatively 
greater resistance to destruction by fire makes the advantages of reinforced concrete so 
apparent that one wonders why timber is employed in the construction of wharfs at all. 

Methods for Obtaining Prices. — But to turn to the other side, viz., economy in 
reinforced concrete, I would like to emphasise a point which in these strenuous davs of 
competition seems to be overlooked, or ra'her ignored, and that is the enormous amount 
of waste which occurs through one of the methods adopted by architects to obtain cheap 
prices for the carrying out of work. An architect prepares the general design of a 
building and sends sunprints of same to four, five, or even six different firms of 
specialist designers, who in turn prepare each their reinforced concrete scheme and 
send out to five or six or more contractors for prices, involving a total of some thirty 
to forty persons, all of whom spend money and time in tendering, etc. Much valuable 
time is also wasted which might otherwise be spent in the construction of the building 
whilst the various schemes and prices are being compared and adjudicated on. 

Concrete Surfaces. — During the few years with which I have been connected with 
reinforced concrete many small problems have been presented to some of which solu- 
tions have been found, whilst others appear almost insoluble. One of these latter is 
the question of leaving the face of reinforced concrete surfaces exposed to view free 
from board marks. If wrought forms thicknessed are used, you have in the case of a 

* NOTE.— The author gave detailed particulars of how he arrived at these figures. 

209 



THE CONCRETE INSTITUTE. [CQNCBET EJ 

wall still to put up onv sick' of the wall board by board, and as you fill up with plastic 
concrete the pressure at the bottom of a 3-ft. lift is greater than at the top, and slight 
lateral deflection is sure to occur on these separate boards, and marks will appear. 
I would suggest that architects should endeavour to persuade themselves that it is 
right for board marks to be there, as they are an expression of the method of con- 
struction, the same as the mortar is in brick joints. 

Centering. — There is another difficulty with centering, and that is the amount 
of props required. I would suggest to contractors that great economies might be 
effected by employing a competent man to design the formwork. 

1 have often heard it said that when floors repeat time after time in a building 
centering can be used over and over again and great economy result, whilst if a slight 
variation is made in the width of the beams and size of columns, extra expense is 
incurred. Now this latter statement is not always true; props under main and secondary 
beams must be left whilst succeeding floors are constructed, so in any case fresh beam 
bottoms have to be used on the higher floors, and no extra beam bottoms are required. 
In order to facilitate the striking of beam sides it will be advantageous when construct- 
ing these to cut them shorter than the distance between the centering to the sides of 
other beams or columns against which they abut. Fill in the space so left with a 
loosely fitting strip battened to the side of beam, and put in the usual angle fillet at 
the junction of beams. When striking the side of the beam take off the last-mentioned 
battens, remove the looselv fitting strip, and the side of the beam can be easily removed 
intact. If some similar method be not adopted, and the beam centering is made a 
good fit, the water in concrete makes the wood swell and jam, with the result that many 
beam sides are broken or pulled to pieces in being taken down, necessitating the expense 
of remaking and possibly new material. If the main beams on a higher floor are 
therefore 1 in. or 2 in. narrower than on the floor below it only means that a slightly 
wider filling-in piece at the end is required. 

Steel Bars. — Another point which makes for economy in reinforced concrete, 
but has more to do with design, is the number of steel bars that have to be handled. 
It will be readily understood that it is just as easy to handle a if-in. diameter bar 
25 ft. long as it is to handle one that is only 1 in. diameter, as the weight is im- 
material ; each requires two men to fix it in a beam, and eight bars take twice as 
long to put in as four, so that from the point of view of economy the four if in., which 
give the same tensile resistance as the eight 1 in., should be used in preference. 

I have only covered some of the ground there is in this question, but I trust that 
what I have said will be of some use, and if it will promote an interchange of ideas, 
as I trust it will, some interesting information may be forthcoming in the discussion. 

DISCUSSION. 

The President observed that what they had to do was to impress the public with the fact 
of the economy of reinforced concrete, and to impress themselves with economy in reinforced 
concrete, and then the former economy would be improved by the latter. Compared with steel 
frame buildings there was generally a considerable saving in time because the reinforcing 
metal was invariably kept in stock, while for the steelwork the larger beams and stanchions 
had to be made to order, and very often the designer had not considered which sections could 
be obtained from stock, and which would have to be waited for until the rolls were next put 
in. A considerable saving of time might be effected by observing that and utilising stock 
section-.. 

He was glad 'hat th<- author called attention to the waste of energy or money caused by 
the architect or building owner inviting competitive schemes from a large number of specialists 
instead of taking counsel from one only, or a! any rate from a limited number. 

Mr. Percy J. Waldram, F.S.I., said the true- economy of any material expressed in 
monetary term>> was of the utmost importance to structural engineers, not only because they 
were entrusted with tin- judicious expenditure of their clients' money, but more especially 
because monetary economy and safety were so often synonymous. To take one example, that 
of reinforced concrete T-beams for moderate spans and loads, the practical designer gave 
those a generous proportion of depth to span, 1/10 to 1/12, using quite a low percentage of 
tensile rein fort emenl . because thai gave a much cheaper beam than shallow depths with 
reinforcements up to or over the economic ratio. In such beams, under working load, only 
the reliable steel received it- working -stress, whilst the comparatively unreliable concrete was 

2 10 



111 



CONMkMH IIONA1. 



ECOSOMY IN REINFORCED CONCRETE. 



stressed verj lightly. In the more expensive shallow beams, with, say, i pel cent. <>i 
tensile reinforcement, the concrete was fully stressed under working loads, while the 
gol off lightly. The authoi was to be congratulated upon his frank admission thai reinforced 
concrete did not spell a monetary advantage in everj situation. The instances of monetary 
saving which he gave wen- al firsl sight extremel) striking, bul when thej were closelj 
examined they became, to say the least, somewhal less convincing. Alternative estimates 
were extremelj misleading unless the) referred to comparable designs similarly priced. It 
would appear thai excellenl design in the material with which the author was identified had 
been compared, doubtless bj inadvertence, with design Ln structural steelwork, which, he 
thought, might Ik- justly criticised as distinctly and unnecessarily wasteful. 

It was worthy of note that the huge block of offices in Kingsway for the Public Trustee 
was one of the steel frame buildings which, according to the author, were so ruinouslj 
uneconomical. One was forced to ask why the interior floors were of the discredited filler 
and steel beam type if the Office of Works were convinced that reinforced concrete would have 
saved such huge amounts of the public money of which they were the custodians. 

Mr. Percy H. Simco, M.C.I. , asked what Mr. Watson meant by saying that the economy 
of reinforced concrete buildings outside London was greater than inside? Did he mean that 
outside London he worked to a bigger factor of safety than he did inside London, and, if so, 
why should not the steelwork man do the same thing? 

Mr. Ewart S. Andrews, B.Sc, said the Paper assumed good design on the part of the 
reinforced concrete designer and rather pointed out the failings of the steelwork, which a good 
steelwork designer should not make. 

Mr. Morgan E. Yeatman. M.A., remarked that, in advocating a smaller number of 
large rods in preference to a larger number of small rods of the same area, there was one 
precaution that should be taken : not to use too large rods in a short beam, because they must 
have sufficient area in proportion to the section of the rods for the strength to be taken up from 
the surrounding concrete. 

Mr. Archibald Scott, A.R.I.B.A., urged that attention should be given to economy in 
specification. 

Mr. W. A. Green, M.A., B.Sc.Eng., did not think a stress of 600 lb. per sq. in. would be 
allowed in London in a reinforced concrete column. The London County Council would not 
allow a filler joist i| in. wide. 

Mr. T. C. Dawson, M.C.I. , believed the great trouble in getting reinforced concrete 
into use in railway-bridge construction was that railway companies were so nervous about the 
material, and it would be well if the Institute could do something to disabuse the minds of 
railway engineers of that nervousness. Railway engineers believed that if a reinforced concrete 
bridge was over-stressed, as many metal bridges were, it w r ould yield very much sooner ; they 
could not place the same reliance upon reinforced concrete. 

Mr. E. Fiander Etchells, Assoc. M. Inst. C.E., referring to the General Post Office Building 
which had been cited, pointed out that it was exempt from the constructional require- 
ments of the London Building Act, and many tenders had gone to show that, to conform to 
the requirements of the old London Building Act of 1894, was still the cheapest method. The 
Draft Regulations proposed that the stress in a pillar should be 600 lb. per sq. in. on the 
reinforced concrete, and the stress on the steel in the same pillar should be 9.000 lb. per sq. in. 

MR. WATSON'S REPLY. 

Mr. Watson, in reply, said that in his Paper he had taken the Regulations governing 
steel buildings and the proposed Regulations to govern the erection of reinforced concrete 
buildings in London, and he had compared those two. If one took an isolated case of a 
building which was exempt from the Building Act no doubt he could show a greater economy 
on a steel frame than on a reinforced concrete building. Hollow tiled floors were certainly 
much cheaper than steel joist fillers, and probably than slab reinforced concrete floors, but 
still they were reinforced concrete floors. 

W 7 ith regard to the question of building Inside and outside London, the proposed Regula- 
tions governing the construction of reinforced concrete in London were considered by many 
reinforced concrete people to be somewhat onerous, and they thought that the factor of safety 
on a reinforced concrete building constructed in London in accordance with the London County 
Council Regulations became in a few years, not 4, on which it was originally based, but 
something like 10. The factor of safety of a steel building, whatever it was at the beginning, 
certainly did not increase with age. 



21 I 



NEW WORKS IN CONCRETE. 



ICDNCRETEI 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information ivill be presented of neiv nvorks in coarse o/ 
construction or completed, and the examples selected ivill be from all parts of the ivorld. 
It is not the intention to describe these ivorks in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea ivhich served as a basis 
for the design, — ED. 



THE CONCRETE COLUMN BRIDGE AT HUDSON, WISCONSIN. 

The accompanying illustration {Fig. 2) and drawing (Fig. 1) show the construction of 
the St. Croix River Bridge with reinforced concrete columns at Hudson, Wisconsin. 
This highway bridge crosses the St. Croix River, and has seven 90-ft. spans, one 50-ft. 
span, and one 136-ft. riveted steel span truss — all supported on pairs of transverse 
knee-braced, reinforced concrete pier columns. 

There is a special interest attached to these reinforced columns, which are from 
4 ft. to 5 ft. in diameter and varying up to about 60 ft. high. They are supported on 
separate cylindrical piers on foundation piles, and there are also ten 20-ft. viaduct spans 
supported on single bents and towers of special construction and on pairs of concrete 
piers. 

There is an approach fill located between reinforced concrete walls which have 
their footings connected by deep, buried transverse struts. The bridge is 1,016 ft. long 




Fi'^. 1. Construction Details. 
The Concrete Column Bridge, Hudson. Wisconsin. 



with a roadway 18 ft. wide in the clear, which has a grade of 7 per cent, and is 48 ft. 
in the dear above high-water level. The 136 ft. channel span has through trusses to 
give maximum clearance over the channel, while all the 90-ft. spans are deck spans ol 
ordinary riveted construction and ar(; duplicates, except that the east 90-ft. span canti- 
levers one panel beyond the pier support at the shore end to carry the S-in. I-beam 
roadway stringers at points 10 ft. beyond the pier centres. The through trusses are 
Spaced 20 ft. apart on centres, and the deck trusses are spaced 13^ ft. apart, with 
the floor-beams at panel points 10 ft. apart, resting on the top chords and cantilevering 
beyond them. The floor decks have 3-in. transverse planks, supported on wooden 
stringers 20 ft. long everywhere throughout the length of the bridge except in the 
through span, which has I-beam stringers. 

The main spans have top and bottom lateral diagonals, which in through spans are 
square rods and in the deck spans i\ and 3-in. angles. The seven intermediate 
piers for the eight main spans each consist of a pair of vertical reinforced cylindrical 



2 I 2 



TTOS5TUUCT10N A ft 
K F.TMr.lNKKWlNCi — J 



CONCRETE COLUMN BRIDGE, WISCONSIN. 



:,";;;; liav.'oHmu!. 3 ft. in di, tor and ., ft. apart on centres with beanngs «r 

horizontal upper surfaces for trusses 20 ft. apart. 




The upper struts connecting then, about 9 ft. below the top net also as girders, 
with seats 134 ft. apart on the upper surface to receive the trusses of the deck spans. 
tu p n : pr ciinnnrtin£ the deck spans are smaller. 

The P "ers are 8 ft! in diameter and , a ft. high, and each of these extends down 
about 7 ft below the top of the ten foundation piles. The abutment is located at the 

213 



NEW WORKS IN CONCRETE. [CDNCBETE] 



top of a high, steep bank and carries one end of a 50-ft. span at one end of the bridge, 

and consists of a reinforced concrete abutment with wing walls. The other end of the 
bridge is carried on a solid fill 40 ft. long retained between two reinforced concrete walls 
with footings extending beyond both faces and connected at the ends of the wall and 
intermediately every 10 ft. by reinforced concrete transverse struts buried in the fill. 

The tops of the walls project just above the roadway grade, serving as curbs, and 

in them are embedded vertical and horizontal angles for the spandrel posts and braces. 

Adjacent to the retaining walls the three transverse bents carrying 20-ft. viaduct spans 

are pairs of rectangular reinforced concrete piers, with their tops connected by 18-in. 

transverse I-beams embedded in the concrete with the top flanges flush with the tops 

of the piers. . .... 

There are six transverse bents of steel construction between the cylinder pier 
columns and the concrete viaduct piers, and each of them has two battered posts con- 
sisting of a pair of channels with their webs riveted at the upper ends to inclined hitch 
angles on opposite sides by transverse girders, which cantilever beyond the columns and 
support the roadway stringers. The girders are 18-in. I-beams with their bottom 
flanges cut to clear" the column channels and riveted to gusset plates engaging the 
columns and receiving the transverse diagonals. 

The columns are seated on short concrete pedestals integral with reinforced con- 
crete tran>ver>e members that act as girders and struts connecting the columns below 
the surface of the ground. The pier columns were built in wooden forms 14 ft. high, 
raised without removing them as each part of concrete was laid. 

The forms for the upper struts were supported intermediately by falsework seated 
on the lower struts, which were completed long enough in advance to develop girder 
strength sufficient to carrv the wet concrete in the upper struts. The 90-ft. trusses were 
shipped complete from the bridge shop and hoisted and erected by stiffler derricks 
moving down grade from end to end of the bridge. 



2 14 



g 



,o&nm"imktionai. 
enc.i n h kino — , 



NEW hooks. 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the h'Adlnq books ivhiJi luvrr appeared Jurinq the last few months. 



Report of the Advisory Committee on Rural 
Cottages. 

i pre & Spottiswoode, East Har.lm^ Street, E I , 
96 pp.+iv. Price is. 6d. 

Contents. Minnies of Appointment 
Report — Introductory The Cheap 
Cottage Necessary Accommodation 
General Factors influencing the Cost 
of Building- The Requirements of the 
Rural Labourer Design of Labourer's 
Cottage- Structure of the Cottage 
Drainage and Water Supply— General 
Remarks on the Plans. 

The question of suitable rural cottages 
of an economical type is of such great 
importance that a committee was appointed 
by the President of the Hoard of Agricul- 
ture and Fisheries to consider and advise 
the Board on plans, models, specifications, 
and methods of construction for this class 
of buildings, and the report has just been 
published. The committee, appointed in 
November, 1913, was constituted as fol- 
lows : Mr. Christopher Turnor, Mr. Cecil 
Harmsworth, M.P., Mr. Raymond Unwin, 
and Mr. Lawrence Weaver; and Mr. 
Charles E. Yarndell, A.R.I.B.A., was also 
appointed to the committee in March, 1914. 

The general contents of the report are 
given above, and in addition there are 
three appendices and twenty-three designs 
for cottages, together with details of case- 
ment and sash windows. Working draw- 
ings of any of the designs illustrated can 
be purchased at prices ranging from is. to 
2S., and specifications can be obtained for 
id. We do not think this arrangement will 
be welcomed by architects who practise 
chiefly in domestic architecture, as it will 
encourage the speculative builder to dis- 
pense with their services; and, in fact, the 
only thing the architect can do is to pur- 
chase the drawings himself and thus save 
the expense of preparing other designs, 



which would COSt several pounds to 
produce. 

Although the committee appear to have 
gone to considerable trouble in their in- 
vestigations, we cannot s.-iy that we 

consider the report as being at all helpful 
in solving the problem of cheap and 
efficient construction, and, in fact, the text 
appears to stale simply those obvious and 
well-known facts with which every designer 
is familiar. It is too general in its tone, 
and does not deal sufficiently with the 
important details of construction which in- 
fluence the cost in such a manner thai the 
reader is helped to form definite con- 
clusions as to the methods and materials to 
employ. 

We notice that mention is made of 
concrete under the sub-heading of " Novel 
Types of Planning and Construction," and 
the committee have hopes that this 
material will prove economical and satis- 
factory after further experiments, and they 
also suggest the use of concrete in slabs for 
out-buildings, as they are satisfied that 
considerable saving might be effected. In 
spite of these remarks, however, thev do 
not deal with concrete blocks or quote any 
examples of their use for the main struc- 
ture, and no notes are given as to the 
methods to be adopted when this material 
is used. Personally, we do not consider 
the use of concrete blocks as a " novel 
form of construction," and it must be 
considered either an oversight or con- 
servatism on the part of the committee 
that this very practicable and economical 
material has not been dealt with in a 
proper manner. We do not suggest that 
it is the only material to use, or that it 
will always show a large saving over brick- 
work, but we do think it has itself proved 
to be satisfactory and generallv more 
economical, and therefore it constitutes an 
important factor in cheap cottage con- 
struction. 



215 



MEMORANDA. 



CONCkErE] 




Memoranda and News Items are presented under this heading, with occasional editorial 
comment. Authentic news 'will be "welcome. — ED. 



Colliery Electric Lamp Rooms. — In a paper recently read by Mr. Wm. Maurice, 
M.I.E.E., before the North Staffordshire Mining and Mechanical Engineers, and 
reported in the Iron and Coal Trades Review, the author deals at some length with 
the question of the design and equipment of colliery and electric lamp rooms. Under 
the heading " Building Construction " the author stated the following : — 

Local custom is usually the guiding factor in the choice of building materials and 
nothing needs to be said on the point. It is, however, perhaps rather unfortunate that 
the local bricklayer should often be the arbiter of construction methods. The use of 
brick footings, lime, mortar, and conventional bondings continues as though Portland 
cement were non-existent. In 1876, when the Model Bye-Laws were published, Port- 
land cement was very expensive, and not in general use for building operations. 
Foundations were generally of lime concrete, and brick footings w r ere necessary to 
protect the lime concrete from crushing. Now the conditions are altered. Cement is 
so cheap as to supersede lime, and cement concrete being capable of withstanding a : 
greater compressive load than brickwork, the protection of footings is obviously not 
required, since the bricks themselves would crush before the concrete. Consequently, 
footings are not provided for the lamp rooms of which constructional details are given 
in the paper. 

For the foundations of the building the trench is dug to the depth required to reach 
a sound bottom, the labourer undercuts it to an angle of about 6 deg., and then it is 
filled up almost to ground level with cement concrete, all brick footings being discarded. 
Bevelled concrete foundations are stronger, cheaper, and superior to the earlier practice 
in every way. 

With cement mortar text-book rules for bond can be ignored with impunity, because 
the conditions are reversed. The matrix is stronger than the aggregate, and the thicker 
the joints the stronger the wall. The ordinary building brick is porous, absorbing one- 
sixth to one-seventh its weight of water, and if the walls are only 9 in. thick, with 
usual methods of bonding, the headers will carry wet right through the walls. For this 
reason English or Flemish bond is useless for ordinary house construction. In the case 
of small houses the difficulty is often surmounted by building hollow walls of two 4^-in. 
thicknesses with iron ties. If the walls are built in cement this will do, but not if they 
arc built in lime mortar. A more effective method, especially for large buildings and 
where more strength is required, is the grouted wall construction. Two half-brick 
thi< knesses are < arried up a height of 10 ft. at a time (if desired), leaving a cavity as 
with the hollow wall, but only ;, ! in. wide. This space is filled in from above with 
liquid grout, one pari Portland cement to one of sand. 

Some recent lamp rooms have been built of steel girders filled in with brickwork. 
Others have been built with fiat reinforced concrete roofs. 

Kehoe v. Simplex Concrete Piles, Ltd. — This was an action for damages for 
personal injuries im urred by the plaintiff while working for the defendants on Spicer 
Brothers' new building in l»la< kfriars. The plaintiff was crushed between a trolley 
owing, he alleged, to the unskilfulness of the defendants' foreman. The defendants 
contended, however, thai the .undent arose from the plaintiff suddenly and voluntarily 
leaving a safe position for a dangerous one at the critical moment. On the sitting of the 
Court, Counsel informed the Judge that the case had been settled, the defendants having 
agreed to pay the plaintiff ^750, including costs. The plaintiff's total claim amounted 
to something over ,£1,300. 

216 



RETT 5 ** 1 



OCfNCCBTEXSSSfSSSK ' 



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STE^PlLlNGfS 




A 
PLANT 

FOR 
EVERY 

PILE 




A 

PILE 

FOR 

EVERY 

PURPOSE 



THE 

"ZENITH "STEAM FRICTION WINCH 

(as recently supplied to H.M. War Office and elsewhere) 

SPECIAL FEATURES 

Will lift a 4-ton Pile on one barrel [with Claw Clutch) at 65 feet per 

minute. 
Will lift a 2-ton Hammer on the other barrel (with Heywood Patent 

Friction Clutch) at 160 feet per minute. 

Has Screw-down Brakes to suspend Hammer while pitching the pile, and 

vice versa. 
Has Cook's Patent Governor Valve, which prevents engine racing and 

automatically regulates amount of steam according to load. 
Has Link Motion Reversing Gear. 
Is mounted, as required, on flanged or road wheels. 



THE MOST COMPACT & EFFICIENT FRICTION 

WINCH MADE. SEND FOR BULLETIN 





HousEiJfe-j; 



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Please meniion this Journal ivhen ivntincj. 



MEMORANDA. 



[CONCRETE] 



TRADE NOTICES. 

New Locks and Latches. — We have received pamphlets from Messrs. Chubb and 
Son's Lock and Safe Co., Ltd., drawing attention to their patent springless lock and to 
their new patent front-door latch. The latch, it is claimed, has many advantages, such 
as a small and neat key, is easily affixed, is suited to either a right-hand or left-hand 
door, has a dished escutcheon to facilitate entry of key, etc., whilst the patent springless 
lock is an entirely novel form of springless lock, affording, the manufacturers claim, 
amongst other advantages, greater security. 

Fuller particulars can be obtained from Messrs. Chubb's, 128, Queen Victoria 
Street, E.C., or al any of their branches. 

The Cement Gun.— Our readers will no doubt be glad to learn that the Cement 
Gun, concerning which one or two special articles have appeared in this Journal some 
time back, has now a British agent in the person of Mr. R. P. Durham. 

The Cement Gun, which is manufactured by the General Cement Gun Co., is a 
machine for building partition walls, waterproofing and vermin-proofing, trench and 
conduit lining, repairing concrete and stone work, etc., etc. 

The Cement Gun can either be bought outright, hired, or the Company will contract 
for the work. 

A booklet containing particulars of this invention, together with details of certain 
work carried out, can be obtained from the British agent, Mr. R. P. Durham, 36 
Southampton Street, Strand, London, VY.C. 

PUBLICATIONS RECEIVED. 
Russian Equivalent Tables. — A very useful set of tables has been published by 
the Centra! Translations Institute, Ltd. In view of the increasing importance of trade 
with Russia, the issue of information regarding the somewhat complicated Russian 
weights and measures, and particularly of equivalent tables permitting of instan f 
conversion of British weights, measures and money into Russian and vice versa, is o* 
considerable interest to the trading world. The set of tables compiled and published 
is stated to cover all ordinary commercial requirements. In addition to money equiva- 
lents they include the usual tables for weights and measures. 

Thev can be obtained from the Central Translations Institute, Ltd., Danes Inn 
House, 265, Strand, W.C. Price is. net. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum J-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 

The VICTORIA 



is built to last 



WRITE FOR CATALOGUE No. 29. 



THE 



T. L. SMITH Co. 

13, Victoria Street, S.W. 



218 



Please mention this Journal ivherx writing. 



CONCRETE, 



Volume X., No. 5. London, May, 1915. 

EDITORIAL NOTES. 



THE QUESTION OF WIND PRESSURE. 

A very interesting paper was read by Mr. R. Graham Keevill entitled " Some 
Notes on Wind Pressure' before the Concrete Institute in March, and an 
extract is given elsewhere in this issue, together with some notes of the dis- 
cussion that followed. This subject is of great interest at the present time, 
when the constructional design of buildings is being developed on highly scien- 
tific lines, and it is rather surprising that more attention has not been given 
to it, especially as the pressure usually assumed is excessive and tends to pro- 
hibit economical design. It is absolutely essential that some satisfactory 
standard should be adopted in order that designers should be in a position to 
make definite calculations on a basis acceptable to the various authorities and 
in conformity with the results of actual experiments ; and the possibility of indi- 
viduals adopting pressure varying from 10 lbs. to 56 lbs. per sq. ft. would then 
be eliminated. 

There is no doubt that the members of the Concrete Institute are very 
dissatisfied with the existing state of affairs, as will be seen upon reading the 
report of the discussion that took place, and under these circumstances we feel 
that they should make some effort to deal with the subject of wind pressure 
and endeavour to clear up any doubtful points both for the sake of the Institute 
and the engineering profession generally. If the various volumes published 
by writers of technical matter are consulted, it will be found that a great 
difference of opinion exists as to the correct pressure to allow and also as to 
the foi mula for deriving the pressure value from the velocity. The various 
bye-laws and regulations in force are just as unsatisfactory, and it is only 
recently that the pressure adopted in London has been reduced to 20 lbs. per 
sq. It. The figure that has been more generally employed in London than any 
other i- 30 lbs. per sq. ft., and although we hardly agree with Mr. P. J. 
W aldram's remark that a pressure of 20 lbs. per ft. would wipe out half the 
chimneys in London, we do agree that chimneys constructed in accordance with 

B 



.9 



THE QUESTION OF WIND PRESSURE. tCQNCBETEJ 

the provisions of the London Building" Act would overturn under a pressure of 
30 lbs. per ft. super, unless the adhesion of the mortar is eonsidered in the 
calculations, and even then the factor of safety is practically negligible. A 
case actually occurred where a building owner raised a chimney stack above 
the prescribed height and refused to put in a tie as requested by the District 
Surveyor, the latter thereon took out a summons, and before going into Court 
wished to prepare a diagram to prove that the chimney was dangerous and 
would overturn. He considered the pressure as 30 lbs. per sq. ft., and found 
that it would be quite unsafe ; but upon preparing- a second diagram in which 
the chimney was limited to the height allowed in the Act he was dismayed to 
find that this also was unsafe, and his evidence became somewhat unconvincing 
to a magistrate who possessed no technical knowledge. 

It seems very curious that the excessive value of 30 lbs. should have become 
so generally adopted in face of such examples as these, and it can only be 
accounted for by the lack of definite investigations and the uncertainty which 
appears to exist in the minds of all engineers as to what is a reasonable velocity 
to allow for, and how the pressure can be calculated from such velocity. 

We have really made practically no progress in this subject since the time 
of Sir Isaac Newton, as, according to his law p = 00027 V 2 , and at the present 
day this value is still adopted by many writers. According to Rankine 
p = 00054 V 2 , and it is curious to note that with all the advances made in 
recent years the two values of Newton and Rankine are still both adopted. 

There are two modern American text books, each of which is regarded as 
an authority that can be given as an example. Marburg, in his " Framed 
Structures and Girders ", under the heading of wind pressure, gives the value 
as p-- 0*0027 Y J , while Burr and Falk, in the " Design and Construction of 
Metallic Bridges," state that p = 0*0054 V-', and furthermore the authors in 
both cases start with the same assumptions. 

It is quite clear, therefore, that even if a certain known velocity is con- 
sidered there will still be a great difference of opinion as to the pressure that 
would result therefrom. 

The experiments carried out by Dr. Stanton in 1903 resulted in his obtain- 
ing the value of 00027, and there is no reason why this should not be definitely 
adopted until further experiments can be carried out to confirm it, or produce 
a different value of undoubted accuracy. 

During the discussion at the Concrete Institute some interesting remarks 
weie made by Mr. E. Gold, of the Meteorological Ofiice, and he stated that the 
greatest velocity ever experienced in London occurred in January, 1881, when 
it reached 43 miles per hour, and this has never been exceeded since. The 
nearest approach to it was in March, 1913, when a velocity of nearly 40 miles 
per hour was reached, and these facts should be sufficient to show how excessive 
arc 1 he pressure and velocities now generally considered. If the velocity in 
London is considered as 50 miles per hour for the purpose of calculation, this 
according to the formula p = 0*0027 V 2 would only give a pressure of 6| lbs. per 
sq. ft., which is somewhat different to the amount provided for in the regula- 
tions in force, which call for excessive strength and involve waste of material. 

Of course the effect of suction pressure should be dealt with, and this will 

220 



(I 



„ CONSTRUCTIONAL 



THE LATE MR. EDMUND COIGNET. 



materially a fifed the design ol rool trusses and similar members where the 
pressure on the windward side onl) is generally considered. 

Tin engineering student, upon cpmmencing the study of theoretical con- 
struction, would find that he could not take any definite value or method in 
dealing with wind pressure with the certainty that he was proceeding on satis- 
factor) lines, or even that he was following the methods adopted by the 
majorit) of designers, as so many different values are given in text-books, and 
each authority consulted but leads to greater confusion. Such a state of affairs 
is very unsatisfactory, and results in training which is inconsistent, thus pro- 
ducing engineers each working on a different basis and each with a different 
opinion, as is evidenced by the various views of the members taking part in the 
discussion before referred to. As it is not possible for the individual to conduct 
experiments on a satisfactory scale to derive empirical formula' for himself, he 
naturally looks to the Institute of which he is a member to put him in possession 
of information of a reliable character. As the pioneers of scientific construc- 
ts n in this country the Concrete Institute should take up the question of wind 
pressure and its relation to the design of buildings, and endeavour to get a 
standard adopted which is more in conformity with the requisite allowance, 
thus promoting economical design and construction. 

OBITUARY NOTICE. 
The late Mr. Edmond Coignet. 

It is with the greatest possible regret that we have to record the death of 
Mr. Edmond Coignet, which occurred on the 29th March last, in Paris, after 
a serious illness. He will be remembered by all as one of the pioneers in 
reinforced concrete. Mr. Edmond Coignet was well known in London 
personally, owing to his frequent visits to this country, where he endeared 
himself to a large circle of friends. He had a personality which compelled 
many admirers, and this was perhaps largely due to the fact that, apart from 
being an engineer of distinction, his knowledge of the world and his wide 
enterprises outside reinforced concrete construction — i.e., as a banker in finance, 
as a great contractor, as a leader in great industrial schemes — gave him that 
wide outlook which prevented his being too exclusively interested in the 
speciality with which his name is largely associated. 

The late Mr. Coignet studied engineering at the ' Ecole Centrale" of 
Paris. In 1879 he was created Officer of the "Legion d'Honneur," and he 
obtained all the highest awards for his well-known system of reinforced 
concrete. He was gifted with an extraordinary amount of energy, which he 
applied to a large number of branches of human activity. In fact, he was 
not only an eminent engineer for works in reinforced concrete, but he was 
also thoroughly versed in all other branches of engineering. He constructed 
a large number of railways and electric tramways in France, in South America, 
and latterly in Italy. A few years ago he entered into a contract for the 
construction of the Port of Bahia, in South America. This work, the cost 
of which amounts to several million sterling, is not yet completed. 

During recent years his advice was sought by the directors of the " Ecole 
Centrale ' in Paris concerning improvements in their curriculum. He was 

B 2 221 



THE LATE MR. EDMOND COIGN ET. [CONCRETE] 



president of the ' Chambre Syndicale des Constructeurs en Ciment Arme." 
He was also a member of the Chamber of Commerce of Paris. 

Mr. Coignet was not only well known as an inventor and a man of 
great practical experience, but he possessed also a very considerable knowledge 
as a theorist. 

He was awarded the " Baude ' Gold Medal for having defined in a 
remarkably clear manner the basis of the calculation of reinforced concrete in 
his celebrated communication to the " Societe des Ingenieurs Civils de France,' * 
and his theories were confirmed in 1906 by the works of the "Commission 
Ministerielle du Ciment Arme. " 

In 1892 he persuaded the engineers of the Paris County Council to adopt 
his system for the construction of a large sewer at Acheres, near Paris, which 
brought about a considerable saving on the original design in heavy concrete 
masonry. This work, which was visited a few years ago by the Concrete 
Institute, of which Mr. Coignet was an honorary member, was the first large 
sewer constructed in this material. 

Mr. Coignet 's name, however, became universally known on account of 
the monumental waterworks known as the "Chateau d'Eau," which he 
designed and constructed for the Paris Exhibition of 1900, and for which he 
was awarded the " Grand Prix " and a Gold Medal. 

Amongst his numerous patents concerning reinforced concrete we would 
mention, as having an exceptional importance, his patents for piles, the 
application of which in this country brought about a celebrated patent action, 
which lasted several years, and in which Mr. Coignet was finally successful 
before the House of Lords. 

Mr. Coignet 's method of construction has been applied to a large number 
of important works in this country ; amongst others, we may mention, several 
large buildings for H.M. Office of Works. 

He was also the chairman of a bank in Paris, which he created for the 
special purpose of dealing with industrial enterprises. 

Reinforced concrete loses a really great man by his death. 



222 



f y,CONfiTPUri - IONAi: 



PADSTOW PIER. 




REINFORCED 

CONCRETE PIER 

AT PADSTOW. 



By Sir G. CROYDON MARKS, MP. 
Assoc.M.Inst.C.E., M.I.M.E. 



The following article on the Pad stow 
Pier 'will probably be of interest to engi- 
neers, especially as there ivere many 
difficulties to overcome in its construc- 
tion. We ivould add that this important 
structure is one of the latest executed in 
this country on the Coignet System. ~ED. 



The increasing trade of the port of Padstow, on the North-East Coast of 
Cornwall, combined with the developments of the Fishing Industry on that 
coast, made it incumbent upon the Harbour Commissioners to provide for 
further accommodation and to so introduce it as would permit of no inter- 
ruption of their existing trade or any decrease of the accommodation provided 
for the vessels regularly using the harbour. 

The Harbour Commissioners consulted the author, who suggested two 
schemes for securing the increased accommodation — one for a new pier 
running- from the outer arm or jetty of the old harbour, while the other was 
for an entirely new enclosed water area with provision lor a wet dock and gates 
extension that might hereafter be constructed, adjacent to the sidings and wharf 
of the London and South-Western Railway Company. The Harbour Commis- 
sioners decided to adopt their consulting engineer's latter proposal, and obtained 
the Act of Parliament for authorising such new harbour work. 

The surveys and plans for the Parliamentary powers were prepared by 
the author and Mr. Edward C. R. Marks, A.M.I.C.E., M.I.M.E.; and upon 
the working plans and contract being approved by the Harbour Department 




Fig. 2. Site plan. 
Padstow Pier, Cornwall. 



223 



G. CROYDOX MARKS. 



CONCRETE] 



of the Board of Trade, a substantial Government contribution towards the cost 
of the construction was promised and in due course paid. The Parliamentary 
plans provided for a new pier of a length of 800 ft. and a width of 40 ft., having 
two separate lines of rails, with crossings laid on the surface standing about 
25 ft. 6 in. above the level of low-water spring tide. 

After the Parliamentary powers were obtained by the Act of 1910, the 

engineers prepared working 
drawings for a pier to be con- 
structed throughout with concrete 
walls and having ordinary 
rammed filling between them. 
Tenders upon these original 
plans were obtained from a 
number of well-known firms of 
contractors experienced in such 
work, but the author, when 
preparing such plans, expressed 
his opinion to the Harbour 
Commissioners that from his 
acquaintance with constructional 
works that had been carried out 
in reinforced concrete it would 
undoubtedly be less costly and 
equally satisfactory to employ 
reinforced concrete instead of 
ordinary massed concrete for the 
main outer walls. This sugges- 
tion was accepted by the Harbour 
Commissioners, and six firms, 
selected from those who had 
tendered for the original massed 
concrete scheme were asked to 
submit tenders upon new plans 
for reinforced concrete construc- 
tion. 

After very exhaustive en- 
quiries and careful investigation, 
the engineers decided to co- 
operate with Messrs. Edmond 
Coignct, of Victoria Street, 
Westminster, the well-known 
specialists in reinforced concrete construction, in adapting and converting 
their original plans for massed concrete work into new plans for reinforced con- 
crete on the Coignct system, as adopted by that firm for other works in different 
parts of the world. The revised plans and specifications were submitted to 
tender, with the result that the tender of Mr. A. Carkeek, of Redruth, was 
accepted, and this tender, while being not greatly below other tenders upon 




iw.ir 



' - ' ''■[ r^j , V/'-r''U-: i ■•■'%'■'.•.'■'• ■■•u-'l'.'b ~Y, 



Fi^. 3. Section of Inner Wall. 
I'austovv Pikr, Cornwall. 



224 







y, noN.vrpiKTiuNAi: 

«V KN(ilNKK»lNfi^, 



PADSTOW pier, 



the same specification, was some jo per cent. lower than the corresponding 
tender for the ordinan concrete construction upon the original plans. 

The difficulties connected with the construction of the pier wen- verj 
great, owing to exceptionally stormy weather and the fact that the water 
never left a large portion of the heav) foundation and excavation, which con- 
sequently had to be put in with the aid ol sheet piling and colter dams. The 
tide, too, which was, when in, some 25 ft. above the foundation, rendered it 

necessary that all work undertaken should be by night and day shifts of men 
working only between the tides. The work was commenced in July, [91 If 
and completed in June, [914, the contractor's period of maintenance provided 
for by the contract expiring in December, [914. 

From the plans illustrated herein it will he seen that the pier consists ol 
two outer walls constructed in reinforced concrete, having cross-tie beams also 




Fig. 4. Erecting the Reinforcements. 
Padstow Pier, Cornwall. 

of reinforced concrete running from one wall to the other, and having" also 
a number of inside buttresses for the entire length of the walls. The lower 
foundation members were of massed concrete, into which the metal reinforce- 
ments were well tied and embedded, while the concrete surrounding and carry- 
ing the reinforced members of the buttresses was also incorporated with and 
deposited into such solid or massed foundations which rested and also keyed on 
the solid rock of the harbour bed. 

The massed or solid concrete foundations were provided with toes which 
engaged with the rock. It was decided, in order to facilitate the work of 
construction, particularly on account of the varying depths of water met with, 
that massed concrete should be employed throughout for the lower foundation, 
and that such should be of a mixture of four to one wherever the depth of 
the rock was greater than low-water at spring tides, while the height of the 

225 



G. CROYDON MARKS. 



[CDNCBOKJ 




226 



I o r O0N>TPUCnONAU 



PADSTOW PIER, 



massed concrete was made to \.n\ will) the irregular lev-el ol th<- rock. In 
even case, however, the top of tin - massed foundations was carried ;• toot 
abov< low-water to enable the contractors i<> construcl all the reinforced 
concrete work above low-water, the engineers being of opinion ih;it ii would 
be extremel) difficult to properly provide for the construction ol reinforced 
concrete below i lu- level ol low tide. 

The reinforced concrete walls were provided with a continuous meshwork 
of steel bars ol |-in. diameter, while the wall itsell was divided into three 

paro Is supported 1>\ continuous 
horizontal reinforced concrete 
beams 10 in. high and ->o in. 
wide; the buttresses have a 
width of 9 ft. at the base where 
connecting to the massed con- 
crete, and tapered gradually to 
the top of the wall. The entire 
main bars of the beams and the 
buttresses are bound together 
by means of metal cross 
stirrups or double embracing 
loops to offer resistance to 
shearing stress. 

Owing- to the rising and 
falling of the tide amounting- to 
about 20 ft., the walls were 
subjected when standing alone 
to very severe stress, of a 
character even greater in 
degree and extent to that which 
is likely to arise under the 
normal or finished conditions 
of the pier. To provide for thus 
initiallv and thoroughly testing the strength, it became necessary to make very 
substantial provisions for the self-contained stability of the work, both in the 
case of low tide and of high tide, quite apart from the ordinary working con- 
ditions that had to be provided for the load that would need to be carried and 
the stress induced by trains travelling upon the rails laid upon the surface of the 
material held between the walls. 

The beams, panels and buttresses, and all the component parts of the work 
were liberally calculated for resisting inward and outward thrusts, while the 
concrete was composed of a rich mixture in order to prevent the possibility of 
the sea-water attacking the reinforcements when in position. To prevent 
cracks arising from expansion or contraction, expansion joints were provided 
at intervals by forming two buttresses, so that they were adjoining each other 
with a space of one inch between them. Suitable weep-holes were provided 
in various parts of the walls to prevent accumulation of water within. 

The two sectional elevations show the general arrangement of the bars 
disposed in the reinforced concrete. Wherever the foot of the wall and 

227 




Fig. 6. Masked Foundation and Reinforced Walls. 
Padstovv Pier, Cornwall. 



C. CROYDON MARKS. 



fCQNCBETEl 

buttresses rest directly on the rock, a longitudinal footing in reinforced concrete 
is provided consisting of three heavy inverted beams and a slab capable of 
supporting the weight of the tilling, with the object of fixing the buttresses 
in such a way as would resist any stress towards overturning the wall from 
tlie internal pressure at low tide. In positions where the reinforced concrete 
wall and the buttresses rest upon mass concrete, the reinforcements were 
anchored and punned directly into such. A certain number of joints were 
provided to form a good con- 
nection between the mass con- 
crete and the reinforced concrete 
work. The outer surface of the 
walls are protected by pitch-pine 
fenders, 10 ft. apart, arranged 
vertically, and having- also a 
double row of longitudinal 
members between them. The 
face of the reinforced concrete 
walls has a batter of one in 
fifteen, and the upper surface is 
provided with Cornish granite 
coping running the entire length, 
while the dry filling at the back 
of the walls is of hand-packed 
rubble to a depth of about 2 ft., 
the intervening space being filled 
with well-punned spoil from 
adjacent quarries laid in succes- 
sive layers of about 1 ft. Chains 
diagonally disposed with anchor- 
age beams were let into the 
ground, heavy links and rings 
being provided above the surface 
for the use of mooring attach- 
ments for the shipping. 

'I he whole of the granite that was employed was obtained from the 
Cornwall Co-operative Company, St. Breward. 

I he Portland cement was sufficiently fine to pass through a sieve for 
2,500 meshes per sq. in. without leaving any residue, and through a sieve of 
5,( ,25 meshes per sq. in. without leaving mere than 15 per cent, residue. 
Sample test briquettes placed in water twenty-four hours after gauging and 
remaining there until tested were required to bear after 7 days .100 lb. per 
sq. in., and after 28 days 500 lb. per sq in. 

Sample cubes made by the contractor at the beginning of every fresh piece 
of work were made and tested by Messrs. Kirkcaldy, who also tested the 
cement before such was permitted to be used. 

Fresh water alone was employed for the mixing of the concrete, while the 
centering and shuttering were kept long enough in position to enable the 
concrete to become sufficiently hard to maintain itself. 

22H 




Fig. 7. Reinforced Skeleton Beams. 
Padstow Pier, Cornwall. 



g 



.COlN.VIVtK-riONAII 



/M/xsroir /'//;/>•. 



,, , A " "'•'•;""""' was well rammed, so as t, fi , casings and surround 

'" l, '"-; m : 1 »™ deposited graduall) in thin layers; when n m " 

'"77" "' "'•■«•■"<"'. *i„g, a rough facing was left in orte , ,. „ 

r::::' k 'V''': ,un ' u ' - ^^ „,,,,„,.„.. ,,,„,,„,„„,„;. 



ueiorc a new deposil was made 




designed on T/r '"^ ° f the rei " f ° rCed ^^ruction throughout 

d,S Z U ^ S> '? m Were PreparCd Under the writer '* g^eral 

m n tT £ r"' °" d C ° ignet ' Limited ' of Victoria Street, West- 

W E S T T T gm r rS b£ing MeSSfS - C - Rickard and G - H. Reed and 

Mr' F r B vT\, e §eneral Pers ° na ' ^Pervision of the writer and 

w*x. n.. L/. K. Marks. 

229 



E. S. ANDREWS. 



CONCRETE] 



<*m 







r 



PROBLEMS IN THE THEORY J 
OF CONSTRUCTION. 3 

A SEMICIRCULAR ARCH 
CARRYING ITS OWN WEIGHT 

ONLY. i 



By EWART S. ANDREWS, B.Sc.(Eng.). 

The following short article ivill probably be of interest to engineers. — ED. 



In the discussion following the writer's Paper before the Concrete Institute upon 
"' Some Modern Methods of Arch Calculation," Professor Adams asked if a 
mathematical solution could be given to the problem of finding the line of 
pressure for a semi- 
circular arch carrying 
its own load only. 

Regarding the 
ends of the arch as 
hinged, the following 
solution is obtained of 
the problem. If an 
isolated load F (Fig. l), 
acts at a point P on an 
arch A P D, the hori- 
zontal thrust at the 
supports is given by 
the elastic theory of 
arches by the formula 

it — F cos 2 <f>* 

77 

Now let w be the 

weight per unit length 
of the arch ; then the 
weight of a short arc 
subtending an angle 
d <l> at the < entre will 
be w / ;irc w R d d>. 
. ' . Horizontal thrust 
contributed by this 
arc 




Fig. 1. 




Fig. 2. 
A Semicircular Arch carrying its own Wright only. 



* This formula is proved in the writer's " Further Problems in the Theory and I >esign < f Structures '' 
(Chapman & Hall, Ltd.), p. I S6 

230 



fa COM.vnNJCTlONAl} 



PROBLEMS IN THE THEORY OF CONSTRUCTION. 



J II 



,. I\ I ' >s </> (/ </> 



. H / -""" 



7T 






COS </> (/ </> 



"(1 f cos 2 </> ) 
2 



_ -cc R fcj) , sin 2 <+>~| 



. </</, 



+; 



_w R 7r _ xc; R 

- ' 2~ 2 

The total weight of the arch= W = xc X circumference 

— w.ttR 

W 

.' . H= -='1592 W 
2- 



< 

as 

H 
Z 

-6 



71 ■« 



z 4 

J 

ta 

O 

H 
H 

z e - 

S 

OS 

o 



(1) 











































































































/ 




















// 


^Linc cf Pressure 













































































































Z 1 G 

Proportion of Half Span. 
Fig. 3. 



a 



re 



To calculate the ordinate r, 
Fig. 2, of the line of pressure at the 
point P we first calculate the " free 
bending moment " B at P. 

An elemental arc at Q contri- 
butes a bending moment at P equal 
to w R .d6XN M 

= w R d 6 {R cos 6 - R cos a) 

= w R 2 (cos 6 — cos a) d 6 

. ' . Total moment at P clue to 
weight of portion from A to P = 
a 

w R 2 (cos — cos a) d 6 
o 

— wR 2 \ sin 6-6 cos a) 
= wR (sin a — a COS a) 

w 

.' . B () = -—.-AN — Moment of weight 
of arc A P about P 

= (1 — COS a) — wR (Sin a — a COS a) 



231 



E. S. ANDREWS. 



[CONCRETE) 



Now 



WR n v 

(1 —COS a) 
2 



WR 



!sin a — a COS a) 






^- (from (1)) 



= JR 1 7r (l — cos a) — 2 (sin a — a COS a) J 
In using this formula a must be in radians. 
This gives the following values of D for various values of a 



(2) 



(3) 



a 

in degrees. 


30 


45 60 


75 


90 


y 

R 


'328 


i 
•617 '886 


1'074 


ri42 



Fig. 3 has been drawn to facilitate the use of the formula. The radius has 
been taken as unity, so that for any given case we have only to multiply by the 
radius the ordinates of the line of pressure given in the figure to obtain the 
ordinates of the required line of pressure. 

If instead of drawing the line of pressure we wish to calculate the actual 
bending moment B at any point P we proceed as follows : — 

B = B -H.PM 

W 

= Bq — ~ • R sin a 

WR, WR,. x WRsma [( / on 
= - 1 —(l— cos a) "(sin a- a cos a) Lfrom (2) J 



WR 



P 



— cos a) (1*5 sin a — 



a — a COS a) j 

TV J 



At the crown where ^ = 90° this gives 

„_WRU-3) 

or putting L — 2R 
W L 



= '0225 WR 



B 



89 



nearly. 



(4) 



2*2 



[a, CONST] WICI'IONAI- 
lAt.N(.lNl.l P1N(. — , 



REINFORCED CONCRETE QUAY WALL. 




REINFORCED 

CONCRETE 

QUAY WALL, 

SOUTHAMPTON 



We are indebted for 
the folloiving particu- 
lars and illustrations to 
Mr. J. A. Croivther, 
Borough Engineer, 

Southampton. — ED. 



The Quay is being constructed on the tidal portion of the River Itchen, 
for the Corporation of Southampton, by Concrete Piling-, Ltd., of 43, Broad- 
wax Court, Victoria Street, Westminster, to the design of the Borough 
Engineer, Mr. J. A. Crowther, the contract price being- ^3,864. 

It has to support a wall of earth varying in height from 16 ft. to 20 ft. and 
also to carry a surcharge load of road granite to a height of 6 ft. Vessels of 
800 tons can berth at this quay at high tide when a draft of 14ft. is available; 
it is also used to berth the hoppers which carry sludge and refuse out to sea. 

The design, primarily, consists of a double row of king piles, spaced 12 ft. 
from front to back and at 8-ft. centres 






longitudinally, which are connected by 
a deck beam at the head and by a tie 
beam at a lower level. At the back 
of the front king piles, sheet piles are 
driven until a good set is obtained, 
and then the heads are broken down 
and a waling is formed on them, from 
which an inclined slab, 17 ft. in length, 
is formed at an angle of 55 — this 
being supported at the top by the back 
upright. At this point, also, the slab 
is connected to the decking, which is 
9 in. thick and runs the whole length 
of the quay, connecting the heads of 
all uprights and forming a horizontal 
girder, 12 ft. wide, giving great 
rigidity. 

On the front section, haunchings 
are formed at the junction of all 
vertical and horizontal members, but in the back section they are omitted. 
When completed, the quay will consist of fortv-three 8-ft. bavs, with 




Fig 2. Showing Type of Construction. 
Reinforced Concrete Quay Wall, Southampton. 



2 33 



REINFORCED CONCRETE QUAY WALL. 



CONCRETE! 



a short return end formed of a single 
line of 8-in. sheet piles, with king- 
piles at 12-ft. centres, anchored at 
the top by i^-in. steel land ties. 

The decking- will be finished with 
a wearing- surface of granolithic 
paving- and fenders will be bolted to 
the front line of piles, while mooring 
ring-s with chains will be anchored to 
blocks of concrete some distance back 
from the quay. 

The whole of the piles were 
made upon the site ; the king- piles, 
being 30 ft. long- and 15 in. square, 
were reinforced with No. 4 i^-in. 
mild steel bars, and in addition with 
No. 4 i|-in. bars for a length of 
14 ft. to give greater strength against 
bending at mud level. The sheet piles 

Fig. 3. Pile Drivers for Sheet and King Piles. were made ill 14-ft. and l8-ft. lengths 

of 1 8-in. by 6-in. sections, and reinforced with No. 6 rs-in. bars. 

Upon driving the king piles, it was found that a good final set was obtained 





I ig. 4. King Piles on site. 

Rkinforcbd Concrete quay Wall, Southampton. 



234 



[ 



j r CiONM Pill"! ionai: 
«v KN(.1NI-I-W1N(. — 



REINFORCED CONCRETE QUAY WALL. 



at roughh 22 it. below mud level. With a steam driven monkey of ->' tons, 
delivering blows at 1 1 1 * - rate of thirty per minute, a set of .| in. in twenty-four 




/ 



/^*^ji 




Fig. 5. End View, showing Front Uprights, Inclined Slab, and Deckin? 
Reinforced Concrete Quay Wall, Southampton. 



235 



REINFORCED CONCRETE QUAY WALL. 



ICPNCRETEJ 



blows is obtained, this being corsidered satisfactory. For the sheet piles a 
l-ton monkey is employed, giving- a i-in. set for a drop of 6 ft. 

All piles are broken down, the king piles 24 in., and sheet piles 6 in. to 
— 2*00 O.D. for the formation of the 21 -in. by 9-in. waling and the 15-in. bv 
6-in. tie to back pile. The waling is reinforced with No. 6 xe-in. bars, and the 
tie with Xo. 4 rVin. bars. 

The inclined slab is subjected to very little earth pressure, as the natiu al 
slope of the clinker filling behind the quay is roughly 45 ; but on account of 
its great length it is doubly reinforced with rVin. bars at 6-in. centres, and with 
No. 4 rV-in. horizontal transverse binding bars, and No. 2 H-in. bars at decking 
level to form a beam at the top of slab. 

From the waling level 15-in. by i5-in. uprights are formed to carry the 
decking, at a level of 12*50 O.D. This decking is 9 in. thick and is rein- 
forced with H-'m. bars at 6^-in. centres, with short continuity bars on the 
upper surface at 13-in. centres, over the cross beams, w 7 hich are reinforced 
with No. 4 J;|-in. bars, of which two are bent up to take the shear. The 
straight bars are each fitted with No. 8 " Keedon " stirrups of A-in. metal. 

Arrangements have had to be made for concreting around two 3-ft. storm- 
water and sewer outfalls without impeding the flow in any way. 

Spiral bond bars are used throughout for the reinforcement, and these 
being of special steel, stresses of 16,000 lbs. per sq. in. are allowed ; iVin. wire 
links are used in all beams and piles as binding. 

Some delay in the construction has been caused by the rough weather, 
especially the gale on December 28th last, when a considerable amount of 
shuttering and casing was carried away; and on account of the double tides 
in Southampton Water, work on the waling and the driving of piles can only 
be carried on for an hour or two at each low tide. 

The construction is being carried out under the supervision of Mr. A. V. 
Dibble, A. M. Inst.C. E., with Mr. J. Godden as Clerk of Works, Mr. W. 
Watterson representing the contractor. 




Fifl. 6. Completed ISays. 
REINFORCED CONCRETE Quay Wall, Southampton. 



236 



f r CON.N rUlK-TlUNAlJ 
V KNC.1NH WjJMCi — 



CONCRETE IN EARTHQUAKE DISTRICTS. 




REINFORCED CONCRETE IN 
EARTHQUAKE • DISTRICTS. 

REGULATIONS BY THE MINISTRY 
OF PUBLIC WORKS, ROME. 

Technical and Hygienical Rules for the repairing, 
rebuilding, and new buildings of public and private 
edifices in certain earthquake districts in Italy. 



Follovjing upon the earthquake of December, 1908, and also from experience gained 
in previous earthquakes, the Ministry of Public Works in Rome issued in J 909 some 
special rules for buildings in earthquake districts. These rules are comprehensive and 
very strict and cover, of course, all forms of construction, but in this article ive only 
reproduce an abstract from the document, which abstract deals voith reinforced concrete 
in the form of some calculations based on an example of a tivo-story structure in 
reinforced concrete. We also reproduce in abbreviated form a feiv of the introductory 
remarks and general rules.— ED, 



Introduction. 

The disastrous consequences of the last earthquake are certainly to be attributed 
in great part to the unsatisfactory building conditions in the localities affected. 
The narrow streets, the excessive height of the buildings and their bad con- 
struction, the inferior quality of the materials used, were, in fact, so many 
causes that prepared the way for, or at least considerably aggravated, ruin and 
disaster. 

It must also be admitted that the gravity of the disaster was net so much 
due to a lack of rules as to the non-observance of the rules in force. 

in view of these facts, the Government in January, 1909, decided that 
suitable compulsory rules should be issued, based on the experience of past 
disasters ; these rules to be applied to buildings under repair, in course of 
rebuilding-, or entirely new public and private structures. 

For the time being these rules are only compulsory in the communes men- 
tioned in the Decree ; all the other communes of Calabria and the province of 
Messina affected by the earthquake and not mentioned must await the conclu- 
sions of the Commission charged to ascertain whether reconstruction can be 
permitted in these districts, and, if so, under what special restrictions. 

Generally. 

The rules approved by the Royal Decree of April, 1909, are divided under 
six heads: (1) New Buildings; (2) Re-building-; (3) Repairs; (4) Observance of 
Rules already in Force ; (5) and (6) General. 

As far as new buildings are concerned, the following are some of the main 
general principles to be applied : — 

Ari. 1 prohibits the construction of buildings within the limits of soil of 
varying nature or on unstable or boggy soil, or on ground having a steep 
decline. In the following article the maximum height of the buildings and the 
number of floors are determined. 

In view of the fact, however, that for various reasons — as, for example, 
public utility, industrial or artistic reasons- -a greater height than 10 m. 

c 2 237 



CONCRETE IN EARTHQUAKE DISTRICTS. (CQNCKETEi 

might he necessary for buildings not intended for habitation, Art. j allows 
for thin eventuality, providing always that special care is exercised in the 
election of such higher buildings. 

Such buildings must in all cases be completely isolated and must not 
exceed 16 metres in height, unless the special purpose for which they are 
designed — as, for example, in the case of lighthouses — absolutely necessitates a 
greater height. 

The new rules permit of any type of construction, provided that the limits 
of height are adhered to and the building is provided with a complete framework 
standing by itself from foundation to roof and made solid by horizontal bearing 
structures. 

A construction of simple masonry is permitted for buildings of one floor 
only, on condition that special precautions are used. 

Whatever system of framework is adopted, however, it is indispensable that 
the calculations be made with great care, in order that the various parts may 
offer the required resistance. 

[Note. — The rules contain various examples with calculations to serve as 
guidance.] 

Special attention is directed to the foundations, and Art. 4 prescribes that 
new buildings must stand as far as possible on naturally solid ground or ground 
that has been made suitable by special means. 

Art. 5 prohibits the use of fragile materials or materials that are not suited 
for resisting special strains and compression to which they may be subjected 
in seismic regions, and for this reason sack masonry and masonry of natural 
flint stones are excluded, unless the latter are suitably broken and used under 
special conditions. 

Arts. 10 to 17 deal with the various parts of which a building is composed, 
and they exclude the use of arched vaults above ground level, floors, ceiling 
coverings, joining together of the main framework of the buildings, the filling 
in and the final covering of the skeleton of frame buildings or one-story build- 
ings are carefully and accurately worked out. 

The width of streets is also dealt with, so as to provide that, should build- 
ings collapse entirely, there will always be a space in the centre of the road 
free from debris. It was considered that a width of 3*50 m. would be sufficient 
for such clear space. 

Reinforced- Concrete Structures. 

In dealing with reinforced concrete, an example is taken of a two-storied 
building with a double row of rooms built of reinforced concrete with a pro- 
ie. ting rigid framework. 

The principal dimensions of the transverse sections of the building (indi- 
1 ated ;n another part of the rules) are here assumed to be as follows : 

Height of ground floor ... h, 4*50 m. 
Heighl of the first floor ... h„ 4-00 m. 

\\ idth of The chamber, measured from the extreme ornamental ion of the 
boundary walls to the middh of the intermediary wall, and based on this the 
238 






£ 



OOMMVUCnONAE 



CONCRETE IN EARTHQUAKE DISTRICTS 




— 4.00 - 



* -50 ^ 



following calculations are given. The framework consists of three rows of 
pilasters. Those corresponding to the two rows of the facade have a squared 
section of 35 cm. per side, while the pilasters of the intermediary row are 30 cm. 

We will suppose that the pilasters of one and the same row are distant 4 m. 
from axis to axis. The length of the compartment, which has a complete trans- 
verse frame composed of three vertical supports, the beams of the Boor, and the 
covering and the stiffening walls will therefore be the same. 

These walls may be of a single or doubly reinforced concrete, with a space 
between to be filled up, in which case the insertion of the indispensable number 
of diagonals is understood. 

The ground floor is composed of a floor in reinforced concrete of the ordinary 
type, the first floor of a terrace also in reinforced concrete, which may be made 
lighter by the use of hollow bricks with a protecting layer of asphalt over them. 

It is supposed that the tlocr and the terrace and the walls (no matter what 
their stiucture) weigh en an average 250 kg. per sq. m. 

The value of 2,500 kg. /m 3 is adopted as the weight for reinforced concrete'. 

Analysis of the Weights of 11 Chamber of the Building 4 ni. long. — Weight 
of the walls of the ground floor: 2 pilasters, 2 x C35 xo'35 x 4'5° x 2 »5°°- 
2,750 kg. 1 pilaster, o"30 x 030 x 4*50 x 2,500= 1 ,010 kg. 

Weight of the walls on the ground floor obtained by multiplying the com- 
bined development of the length on the surface of the walls themselves by the 
height of 4*50 by the weight per sq. m. of 250 kg. : — 

(8"5o + 12 — 4 x C35 — 2 x C30) x 4*50 x 250 = 20,810 

Therefore the total weight of the walls of the ground floor : — 
2,750+ 1,010 + 20,810 = 24,570 kg. 

The weight of the floor or of the flat roof : — 

8*50X4x 250 = 8,500 kg. 

239 



CONCRETE IN EARTHQUAKE DISTRICTS. [CQNCKETE j 

Total weight of the walls of the first floor, the height of which is equal to 
_ * = 1 that of the walls of the ground floor : — 

f 24,570 = 21,840 kg. 
Calculation of the horizontal forces for the entire Chamber in Tons : — 

^i= T V24*57 = 2 '°5 t - 

Sx = A 8-50 = 071 t. 
R 2 = i 21-84=2731. , 
S 2 = J 8*50= 1 -06 t. 
Calculation of the Bending Moment. — At the floor level, first floor: — 

M, = (s> + i# 2 )/?2=( I ' o6 + 2 ~) 4 = 9' 68 t.m. 
At floor level, ground floor : — 

31! = /?/'' = 2-05X2-25= 4-612 

2 

+ Si 7*1 = 071 X4"5°= 3 -I 95 

+ J R 2 (/2,^ 2 ) = 27 3X 6-50= 17-745 

+ Si (/i 1 -l-^ 2 ) = 1-06x8-50= 9-010 

M. = 34'5 62 t.m. 

St) esses in Vertical Supports due to foregoing strains. — In consequence of 
the bending moments calculated above, the corner vertical supports are subjected 
the one to compression stress and the other to tension stress by a strain which is 

respectively of the value of 9 -=1*19 t. at the first floor and--- — —— 

1 J 8-50 — 0-35 8 50 — 35 

= 4-24 t. at the ground tloor. 

To the stress just calculated must be added that due to the weight of the 
part ol the building under consideration, the weight of the walls of the ground 
iloor only being excluded, this being transmitted directly to the foundations. 

The following loads bearing on the cross section of the pilasters of the 
facade at floor level of the ground floor are deduced from the analysis of the 
weights : — 

Pilaster to ground floor (the weight of the two pilasters being 

*75) T =t - r38 

Pilaster to the first floor, I [-38 =t. 122 

Weighl of each wall of the facade of the first floor (4-0-35) 

4x0-25 =t - 3'°5 

Pressure exercised by the transverse walls, floor, and fiat roof, 
always admitting the zones of concentration to be limited by 
the middle line of the sides, | [2 x 8*50 + (8*50 -2 x 0*35- 

0*30) 4x0*25] ^ (yi2 

Total - t. 12-37 



I nci easing the above-mentioned pressure by 50 per cent., in order to allow 
240 



[/v^A^'i!^] CONCRETE IN EARTHQUAKE DISTRICTS. 

for the dynamic Hint of the heaving slunk, and adding to ii the stress due to 
the horizontal actions, tin- maximum compression is obtained : — 

[•5 x 127,7 I 4 '-'4 2279 t. 
Reducing iliis by 20 per cent, to allow for the decrease ol weight thai may he 
produced by the vertical acceleration, and subtracting from it the strain due to 
the horizontal actions, we have the minimum compression : 

o'<S x [2'37 424 506 t. 

Effect of the Local Actions. Bending produced by the horizontal lories 
distributed along the pilasters of the facade. 

Horizontal stress applied to each pilaster of the facade at the ground floor 
corresponding to the mass of the pilaster itself, to that of the front wall and to 
half the transverse wall, supposing- that its action is subdivided equally between 
the three vertical supports : — 

TV[ r 3 8 + (4- '35) 4'5 oxo ' 2 5 + ^ (850-2 XC35 -0*30) 4*5° x °' 2 s\ = °' ()( J l - 
The bending moment produced by the above-mentioned stress is considered, 
according to custom for the calculation of the half-morticed joists of reinforced 
concrete, equal to 

j 1 ^ 069 x 4*50 = 0*310 t.m. 
Calculation of the Pilasters. — Limiting the enquiry to the pilaster of the 
ground floor facade, we have : — 

Maximum compression ... ... ... =t. 22*79 

Breaking stress : £ (Rj^ + S 1 4- R 2 4- S 2 ) ... ... — t. 2*20 

Bending moment ... ... ... ... =t.m. 0*310 

Considering the very advantageous hypothesis, however, on the basis of 
which the enquiries have been conducted, and taking - into account the inevitable 
deficiencies cf the connections due to the opening's in the walls, it is not wise to 
make too great an allowance by this method, which is an exceptionally favour- 
able method of considering the resistance of a building - . 

The pilasters of the reinforced concrete are therefore calculated as if they 
were not reinforced, and with a safe stress of 25 kg. /cm. 2 . The result of this, 
a being' the side cf the squared section of each pilaster, is 

22,790 3 1,000 f 6 



2 3 

a a 



= 2 



and therefore a = 34 cm. 

Provision must be made for the disposition and percentage of the framework 
by the usual criteria, the solidarity of the various resistant parts of the frame- 
work being- better ensured, however, than usual. 

Calculation of the Diagonal Framework. — If the stiffening were obtained 
for the whole or in part by means of diagonal frameworks, they would be calcu- 
lated on the basis of the breaking stress, corresponding to the horizontal section 
which it meets at half length. 

At the ground floor we have breaking stresses at 2*25 m. from the floor : — 

V = \ R 1 + S 1 + R 2 + S 2 = 5S2 t. 

If, therefore, there is a single diagonal in each quadrilateral network, or, 
better, if, there being two, it is supposed that only the compressed diagonal 

241 



CONCRETE IN EARTHQUAKE DISTRICTS. [CONCRETE] 

works, we have as an expression of the strain, the inclination of 45 being: 
presc rved : — 

h 5-22 N 2 = 3-91 t. 
Having- recourse to the formulae of the solid uppermost weights for the 
maximum length of the diagonal / = 450 \ 2 cm., and the intermediary hype- 
thesis between that of the morticed extremities and that of the said extremities 
being- free to turn being- considered as acceptable, we have for a square section 
of side a (everything being expressed in cm.) for a coefficient of security equal 



to J:- 



1 '» E 1 4 
5 9 io = i 27r - T i_ a 

A squared section of about 14 cm. a side is therefore deduced, to which a 
more or less strong framework will be applied, according to whether the diagonal 
is intended to resist tension also, and whether the wall does or does not give a 
certain confidence. 

Calculation of the Floor and Terrace Beams. — This does not present any 
singularity in respect to the usual calculations of buildings in armoured concrete, 
except in regard to the appreciation of stress weight, which must be assumed 
to be 50 per cent, greater than its effective value. 



242 



rj,CTON5rUUCTIONAI. 
1A t^MClNKf.PlNf. — , 



THE WAR IN RELATION TO BUILDINO. 




1 



THE WAR 

IN RELATION TO 

BUILDING. 

[Contributed.] 



The great War has had such terrible consequences for so many towns and -villages in the 
areas affected by military operations that it is to be feared that the future operations of the 
armies will have equally serious results in many towns still untouched. The war on two 
fronts, for -which Germany had so cleverly prepared, has already resulted in the loss of 
hundreds of thousands of lives, the wholesale destruction of houses, buildings and toivns, 
and a fabulous loss of material -wealth generally. What may happen in the future it is 
impossible to do more than surmise. The future damage, however, to structures and towns 
in the legitimate conduct of the ivar is likely to be enormous / and, as the matter is of 
considerable interest to constructional engineers and concrete specialists from several 
points of view, the following observations by a correspondent during a recent visit to a 
part of the war-devastated area may be of interest, as affording some idea of the effect of 
bombardment and fire on the toivns affected. — ED. 



One of the first impressions on entering - a bombarded or destroyed town is 
of desolation. What was once a busy town, with conveniently planned buildings 
and well-arranged streets, is now a tumbled-down collection of bricks and 
mortar, twisted ironwork, bent girders, and calcined stonework, giving the 
suggestion of earthquake and fire and subsequent demolition on a large scale. 




Fig. 1. Senlis after the Passage of the Germans, September, 1914. 
The War in Relation to Building. 

One of the places reached and partly destroyed by the Germans in 
September last is Senlis, a charming little city situated on the Xonette, about 
one hour north from Paris by train. Here an opportunity is afforded of seeing 
what has been done to peaceful towns and of observing the effect of bombard- 

H3 



THE WAR IN RELATION TO BUILDING. 



ICDNCRETE] 



ment and incendiarism, though, as already slated, fortunately only one part 
of the town has been destroyed, the old and most interesting portions escaping 
with little or no injury. The railway station has been entirely gutted by fire, 




Fig. i. The Faubourg St. Martin. 1 
The Wak in Rki.ation to Building. 



though the main walls are practically intact, and outside the building lor some 
distance there is nothing to remind (me of war. Il is not until the principal 
street of the town, the Rue de la kcpubliquc, is reached that the work of 

2+4- 



n 



t con.viuuc-i ional 
i:ngjnkl kmm. — , 



THE WAR IN RELATION To BUILDING. 



ihc invader is seen .11 its best, or worst. Smashed and burnl buildings are 
seen <>n both sides oi the nunc street, with an occasional structure, more 
or less untouched, lclt standing*. Ruin and desolation confronl one ;ii each 
step: roofless dwellings, with boarded-up windows and doors, charred 
beams, twisted ironwork, heaps ol brick and stone desolation complete. Some 
buildings, <>l course, have withstood 1 1n- ordeal better than others, and 
some stand to illustrate what may be termed the "curiosities of resistance," 
but the destruction is so thorough, and is such emphatic evidence of a 
determination to destroy, thai il is surprising thai the main part of the town 
is untouched. The cathedral has sustained some damage, hut thai can he- 
restored in a short time at a trifling cost, while the rebuilding of the Rue 
dc la Rcpubliquc, the Rue Bellon, and the Faubourg St. Martin will take 
months unless an army of workmen is employed. When it is remembered 
that what has been done in Senlis has been carried out with very much mere 
thoroughness and much more completeness in hundreds of other towns and 
villages in France and Belgium, it will be realised that there will be full scope 
for the arts of peace when the arts of war are at rest. The demands that will 
be made for skilled workmen and for building- materials of all kinds may have 
the effect of increasing - cost, but it will without doubt keep engineering and 
building industries busy for a long" time to come, and will necessitate the erec- 
tion as an immediate necessity of buildings to serve simple requirements at as 
low a cost as possible and which shall be fire-resisting as well. A visit to 
towns in the war area affords ample evidence in support of pre-conceived 
ideas, especially that nothing- can withstand bombardment with modern shells, 
provided that the bombardment is properly carried out, but that reinforced-con- 
crete work does not collapse in the hopeless way in which ordinary buildings do. 
Moreover, with buildings subjected only to fire, reinforced concrete has an 
immense advantage over ether materials. 




Fig. 4. The Sous-Prefecture, Rue de la Republique. 
The War in Relation to Building. 



245 



THE CONCRETE INSTITUTE. 



[CONCRETE] 




'I' 77 ] 



fflBffllg: 



RECENT VIEWS ON 
CONCRETE AND REIN. 
FORCED CONCRETE 



THE CONCRETE INSTITUTE, 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes, — ED. 



THE CONCRETE INSTITUTE. 

SOME NOTES ON WIND PRESSURE. 

By R. GRAHAM KEEVILL, A.MJ.Mecb.E., Works Department, Admiralty. 

The following is an abstract from a Paper read at the Fifty-eighth Ordinary General 

Meeting of the Concrete Institute. 

\\ end, as we all know, is caused by the horizontal, vertical, and rotatory movements 
of the atmosphere which are set up by the alterations of density, temperature, vapour, 
and possibly gravity. 

'I he atmosphere as far as present-day knowledge carries us extends upwards from 
the surface of the earth, gradually becoming rarefied until it merges into the eternal 
interstellar space. Luckily, we are only concerned with movements of the air com- 
paratively near the earth, otherwise our subject would be vast indeed. 

It may be said that our modern knowledge extends backwards only so far as the 
destruction of the original Tay Bridge in 1879. 

It will he interesting to recall, briefly, the disastrous Tay undertaking as far as 
ii concerns us, and sec what the engineers of those days 35 years ago- knew about 
wind pressure. 

The bridge was opined for traffic on Ma\ 30th, 1K7K, the total cost being about 
£3S°i°° 0, ' ! consisted oi lattice girders, with one exception of large span, carried on 
groups of cast-iron columns braced together, which in turn were carried on masonry 
foundations. The rail level ai the highest point was ss ft. above high-water level, and 
there were altogether 85 spans. 

On December 28th, [879, whilst a Main was on the bridge and a "gale of 
exceptional severity was blowing," one or more of the piers gave way, bringing down 
eleven 245 ft. span and .>.>~ ft. span girders, precipitating the train and 74 people into 
the Tay. A Board ol Trade Inquiry was held, and it was stated in the Commissioners' 
conclusions thai " engineers in France made an allowance of 55 lb. per sq. ft. for wind 
pressure, and in the United States an allowance of 50 lb." 

The evidence given showed thai the knowledge of wind and wind pressure at this 

period was in ;i state of i haos. 

An endeavour was ;it once made by a Hoard of Trade Committee to put matters on 



24.6 



[A'kSoSkV'J'.n^^I some NOTES ON WIND pressure, 

a satisfactor} footing. After examining wind records, thej <>n May 20th, 1881, 
recommended : — 

14 That ftu* railway bridges * >r viaducts a maximum wind pressure «>f 56 11*. per 
sq. ft, should be assumed for the purpose »»i calculation." 

This immediately came into force for railwaj work, and was also adopted generally 
for structures on public works, although such adoption was pun ly arbitrary, or specified 
in local by-law s. 

Much opposition was raised to this standard <>1 pressure, because it was considered 
excessive and not justified by experience of existing structures. As far as buildings are 
concerned, the horizontal pressure assumed for designing has gradually been reduced to 
the 30 lh. per sq. ft. now often taken. 

There are three methods for the measurement of wind: — 

(i) Velocity measured by the Robinson anemometer. 
(ii) Pressure measured by a pressure tube anemometer, 
(iiii Pressure measured by a plate or board set face to th< wind. 

Considering (i), the anemometer that hears his name was invented by Dr. Robinson 
in 1S46, and is hy far the most used of the various instruments which have been 
produced from time to time. It consists of four aims at right angles; at the end of each 
arm is a hemispherical cup. In the standard pattern the cups are () in. diameter, whilst 
tlic arms are 2 ft. long. The arms are mounted on a spindle, which rotates with the 
movement of the cups in a wind, and is geared to mechanism for counting the 
revolutions made. The cups are set to face all one way, so that the concave face oi one 
cup is always presented to the wind, and consequently as the wind pressure within the 
cups is greater than on their convex backs, rotation is caused by quite a small wind. 
This instrument therefore measures direct velocity, and Dr. Robinson, after experiment- 
ing, stated that the velocity of the cups was one-third the velocity of wind for all 
instruments whatever their size. This is now known to be a fallacy, with the result 
that practically all records of velocity prior to 1902 were incorrect and generally much 
too high. 

The discovery that the factor, 3, for the Robinson anemometer was incorrect is 
due to the experiments carried out by Mr. Dines, and since confirmed bv other 
authorities. 

These experiments consisted of placing anemometers on hotizontal arms, which 
were rotated by means of a steam engine; 14^ revolutions of this " whirler " constituted 
a half a mile of space, whilst great care was taken to ensure accuracy in the results. 
The number of turns of the whirler and the revolutions of the anemometers, both of 
which were counted automatically, determined the relation between the distance travelled 
and the revolutions of the anemometers, and thus the value of the new factor, 2*2, was 
obtained. 

The outcome was that the Wind Force Committee of the Roval Meteorological 
Society in 1902 adopted the factor 2*2 instead of 3 fot the Standard Robinson 
anemometer. Thus when the old factor was used, and the instrument indicated, sav, 
a velocity of 60 miles per hour, the use of the new factor reduced the velocity to 44 miles 
per hour. Converting these velocities into pressures by the formula P = o*oo3 Y-, the 
60 miles per hour velocity gives io\8 lb. per sq. ft., whilst the velocity of 44 miles per 
hour gives a pressure of 5*8 lb. per sq. ft. This rotating anemometer has one great 
disadvantage, in that owing to the inertia of the instrument it does not record gusts of 
wind, which may have a much greater velocity than the average values shown bv this 
instrument. 

Another type of instrument is the pressure tube anemometer invented bv Mr. 
Dines. This instrument automatically records all the varying pressures of the wind, 
and consequently all gusts and lulls that occur during a gaie whatever the velocity of 
the wind may he. The principles upon which the design of this instrument is based 
are that when the wind blows into the open horizontal mouth of a tube it causes an 
increase of pressure within it and in all air-tight arrangements connected with it. On 
the contrary, if the wind blows horizontally across the open mouth of the vertical tube, 

2 -f7 



THE CONCRETE INSTITUTE. 



CTTCEETE 



the column of air within the tube rises and the pressure is reduced within it, and in all 
air-tight arrangements connected with it. The great advantage of this instrument is 

that it not only gives a record of all phases of wind, but a practically perfect exposure 
can be obtained by mounting it on a high pole. 

The third type of anemometer is like the second type, a pressure recorder, and is in 
general use although now practically obsolete. This type consists of a board or plate 
which by means of a weather vane is kept facing the wind. The back of the board is 
fitted with springs which keep the board up to its work. The wind acting on the face 
of the board drives it backwards,-- compressing the springs; the pressure is then 
measured and recorded automatically by the movement of the board or the compression 
of the springs. 

This type of pressure boards was used at the Forth Bridge during its construction. 

When Sir B. Baker, in conjunction with Sir John Fowler, undertook the responsi- 
bility for this great structure, it became necessary to ascertain as nearly as possible 
what would be the probable wind pressure on the bridge in the exposed position on 
which it is sited. 

He accordingly erected, on the top of the Old Castle on Inchgarvie, three 
anemometers. The principal one was 20 ft. long by 15 ft. high, approximately the size 
of the side of a railway carriage of those days, erected vertically with its surfaces facing 
cast and west, this direction being the most unfavourable from which the wind can 
strike the bridge. This board was hung in a frame and was carefully adjusted and 
balanced and fitted with lour springs at the four corners to adjust the board to its 
normal position. The movement of the board was communicated to the registering" 
apparatus by means of wires. 

To ascertain to some extent the effect of small local gusts plates were fitted of 18 in. 
diameter in holes cut out of the centre of the board and at the top right-hand corner, 
and arrangements made to register the pressure on them separately. 

A circular plate with an area of 1^ sq. ft. was erected to face the same direction, 
and 8 ft. away from the large board, and provided with means for registering the 
pressure. 

The third was a revolving gauge also with an area of i| sq. ft. and fitted with a 
vane so that it always faced the wind. 

The results from the Forth Bridge are interesting and valuable in that they show 
records of an exposed position at considerable differences in height and width. From 
a consideration of them with other reliable information now available, they appear to 
be high in value and to be influenced by gusts and possibly by some momentum of the 
plates of the anemometers. 

Tn order to see at a glance the results valuable to us, the velocities have been 
reduced to pressures by the formula P = o - oo3 V 2 . 

It will be of interest to note that the greatest velocity recorded since the Meteoro- 
logical Office has been at South Kensington is 54 miles per hour, on July 28th, 191 1, 
which is equivalent 1o a pressure of about 8*75 lb. per sq. ft. 

The relation between coast and inland winds is a practical question which often 
arises when an importanl structure is to be designed in some locality where building 
regulations are of an elementary nature, or non-existent, and where the onlv guide is 
the possession of reliabli information, but which has been taken at one or more exposed 
Stations near the coast, whilst the proposed Stl'UCtun may be sited some distance inland. 
Dr. Shaw s,-ivs thai "speaking from the daily experience of weather maps we 
may sav thai a weslerh wind of force 8 at an exposed western station will be repre- 
sented at inland or easl coast stations by a wind force of 5. The corresponding 
reduction of velocity is from 42 to > 1 miles per hour. Provisionally, therefore, we may 
say that the surface wind velocity (thai is winds tin! will affect a structure) at a 
reasonably well-exposed inland station, or al a coast station lor an off-shore wind, is 
reduced to one-half the velocity of an open coast station." As pressure is dependent 
on velocity it follows that the pressure will hi- reduced to a corresponding amount. 

When dialing with a building of large exposed area there is often a difference of 
opinion, in the absence o\ regulations, as to what wind pressure lo adopt i.e., whether 
iIm maximum average veloi i'v or the greatest gust. There is little available information 

248 



J, CONM UlKTIONAi: 
<v iMilNIl PINO — 



SOME SOTES ON WIND PRESSURE. 



as to wli.it m.i\ be termed the area of a gust, but ii is considered to !><• comparativelv 
small. In a well-designed and well-constructed structure it would appear to be good 
enough to take the maximum velocity, and trust to the continuil) of the structure to 
distribute local gusts. In Professor Henn Adams's engineers' handbook there is a 
table for reduction "I wind pressures According to heights .m<| widths of a building. 

Ihi knowledge ol wind at low and high altitudes the latter concerns the flying 
men more than anybody else — has made greal progress in recent years. Investigations 
on a large scale have been carried out by \)v. Shaw's department, and it is now possible 
to calculate the velocity of the wind at high altitudes, when the surface velocity is 
known. "As a rule (but with exceptions) the wind increases rapidly as the surface 
is left, up to two, three, 01 four times the surface velocity. The increase of wind 
appears to be in direct ratio with increase of height. 

" For the .station at Ditcham Park it has been found that — 

v.-4-v. 

ho 

where V/, = velocity at height h above sea-level, 

h = height of a well-exposed anemometer above sea-level, 
Y s = velocity recorded by the anemometer. 

" The corresponding law for other places is not yet known. There is, however, a 

consensus of opinion that velocity increases with height, by factor and not h\ constant 
addition. A likely formula is : — 

y- H+g y 
a 

where H = a height above ground, 
V = velocity at H, 

V s = velocity recorded by the anemometer, 
a — constant. 

" From the examination of observations at various stations the following curious 
conclusion has been drawn : the constant a for the purposes of rough approximation 
may be taken to be the height of the station above sea-level.'" 

Another method of obtaining a knowledge of the wind is by a system of observation. 

In 1805 Admiral Beaufort, Hydrographer of the Navy, devised the scale of wind 
force which bears his name. 

With the passing of the sailing ship and the present universal use of steam the 
Beaufort scale has lost entirely its original significance. The scale, instead of passing 
into oblivion together with the ships that it was designed for, has become rejuvenated, 
and is now the British standard for estimating wind force on land and sea all over the 
world. 

We are not concerned with wind at sea; the land part of the specification is as 
given in the accompanying table. 

In the report of the Meteorological Committee for the year 1006 it is stated that 
during the investigation into the Beaufort scale it was found that when " the velocities 
arrived at empirically, as the appropriate equivalents of the Beaufort numbers, were 
plotted upon a diagram and a working curve drawn to represent them, the curve so 
drawn turns out to be very nearly identical with that represented b\ the algebraical 
equation V=r87^/B3, where B is the Beaufort number 1 and V is the hourly wind 
velocity in statute miles per hour. Adopting Mr. Dines's factor 0*003 for obtaining the 
wind pressure in pounds upon a square foot, it follows that the relation between the 
Beaufort numbers and the wind pressure, P, is expressed by the comparatively simple 
relation — 

P=0'0T05 B 3 . 

24.9 



THE CONCRETE INSTITUTE. 



tCDNCEETEl 



Description 
of Wind. 



Specification of Beaufort's Scale for 
Use on Land. 



=2-2 = 
.S|s> 

<^ 5 M 
o t/> 6 

T3 % 



"* cr >> 
« H g 

(U JJ c 



o 

w I . 

CD n 

tvpq 

(/) s. 

o > 



> 



> 



73 

d 

« D jl 

s.s £ 

a; ,2 w 

'o -^ JH 

x> >.B 
> 



6 



9 
io 
n 

12 



Light 
breeze 



Moderate J 
breeze 



Strong 
wind 



1 Gale 

forces 



Storm 
forces 

Hurricane 



Averages. 
Calm; smoke rises vertically ... ... o o 1*5 

Direction of wind shown by smoke drift, 

but not by wind vanes ... ... ... o-i 2 4 

Wind felt on face ; leaves rustle ; ordinary 

vane moved by wind ... ... ... o-8 5 9-5 

Leaves and small twigs in constant motion ; 

wind extends light flag ... ... ... 0-28 10 15 

Raises dust and loose paper ; small branches 

are moved ... ... ... ... ... 0-67 15 24 

Small trees in leaf begin to sway ; wavelets 

form on inland waters ... ... ... 1-31 21 30 

Large branches in motion ; whistling heard 

in telegraph wires ; umbrellas used with 

difficulty 2-3 27 28 

Whole trees in motion ; inconvenience felt 

when walking against wind ; umbrellas 

discarded in exposed places ... ... 3-6 35 46-5 

Breaks twigs off trees ; generally impedes 

progress 5-4 42 56 

Slight structural damage occurs (chimney- 
pots and slates removed) ... ... y-y 50 66 

Seldom experienced inland ; trees uprooted ; 

considerable structural damage occurs ... 10*5 59 

Very rarely experienced ; accompanied by 

widespread damage ... ... ... 14 68 

Above 17 Above 75 



11 Thus, if all the steps in this intricate investigation have been accurately followed, 
there appears to be underlying Admiral Beaufort's original specification the simple 
relation that the numbers selected are proportional to the cube root of the wind 
pressure. " 

The question of the r< lation of wind velocity to wind pressure cm now be considered. 

The formula already quoted in this paper is P = KV-\ where P equals the pressure 
per sq. ft., V the velocit) of the wind in miles per hour, and K a constant. 

It is the value to be taken for K thrd has caused a vast amount of discussion\and 
research in n < enl years. 

It can now h'- accepted thai for flat solid surfaces placed at right angles to the wind 
the value for K is 0*003 or 0-0032. 

The value for K obtained by Dr. Stanton is 
experiments carried out at the National Physical 
him in the M.P.I.C .11. , vols. clvi. and clxxi. 

The conclusions arrived at wore thai '" th< 
supposing that the mean intensity of pressure on similar surfaces of area greater than 
1 sq. ft., exposed to the wind, is independent of their actual dimensions." 

Interesting experiments to obtain the distribution of air pressure were made l>v 
Dr. Stanton in a uniform current of air <.n small models representing (dosed buildings 
with roofs at 30°, \-,'', and 6o° to the horizontal. These may bi briefly summarised 
as follows : — 

Model with 30° roof. Plus pressuri on the windward vertical wall and oxer about 
the middle third of the slope of the roof on the windward side. 

250 



ie result of an elaborate series of 
.aboratory, ana fully described bv 



re appeared to 



reasons 



for 



J, lONyikMICI ION A I 
« 1 NGINhl-WlNCi -^ 



SOME NOTES ON WIND PRESSURE. 



Minus pressure over i he remainder <>l the windward rooi slope, and on the leeward 

slope ;iihI Wall. 

Models with 45 and 6o° roofs. Plus pressure on the windward vertical wall and 
slope, except .it the ridge, where it becomes minus. 

Minus pressure on the roof and wall oi the leeward side. 

Whilst these results were obtained with an artificial current oi air, Dr. Stanton 
says that "the action of wind is no doubt more complicated than thai of a uniform 
current of air; yet it stems probable that in displacements of considerable intensity, 
such as gales, the conditions of a uniform cuirenl may be approximate!) fulfilled, so 
that the distribution of the wind pressure on exposed structures may be regardi d as that 
due to a uniform cui rent . " 

Further experiments were carried out on a model roof with slopes of 56 sq. ft. in 
area, and so arranged that the angle of the slopes could be varied. 

Values for K for use in the formula P K\ , where P equals the normal pressure 
on the roof in lhs. per sq. ft., and V equals the velocity of the wind in miles per hour, 
were obtained, SO that it is only necessary to know* the maximum velocity of the wind 
at any site in order to arrive at the pressures on a proposed building at the site. 

Another phase of the investigations at the National Physical Laboratory was an 
endeavour to throw light on the much-vexed question of the shielding effect of membi rs 
of a lattice girder placed behind each other, and the effect; of a windward girder on a 
leeward girder of a bridge. 

From the small models it was found that with two circular plates placed \\ times 
their diameter apart the total pressure was " less than 75 per cent, of the resistance of 
a single plate. " 

On increasing the distance to " approximately 2*15 diameters the total pressure was 
equal to that on a single plate." 

Again increasing the distance to "5 diameters, the total pressure was only 17S 
times that on a single plate." 

" Experiments on square and rectangular plates gave corresponding results, it bi ing 
found that the shielding effect of long rectangles was considerably less than in the case 
of circular plates, but in all cases the maximum shielding effect was observed wh< n the 
plates were at a distance apart of approximately 1*5 times the least cross dimension." 

Investigations were made on model lattice girders subjected to the uniform current 
of air. The " experiments were made on a single girder, and on two parallel girders 
with and without a roadway, normal and inclined to the direction of the current. The 
shielding effect of the windward girder is very considerable, for both normal and 
inclined currents. When the two girders are connected by a roadway and are at a 
distance apart equal to the depth of the girder the pressure on the leeward girder is 
15 per cent, of that on the windward girder, and at twice this distance the pressure is 
25 per cent, of that on the windward girder. The effect of the roadway appears to 
diminish the total pressure on the girders. When the direction of the current is inclined 
to the plane of the girders the resultant normal pressure is increased for small angles 
of obliquity, but not to any i*reat extent, the value of the normal pressure when the 
current makes an angle of 75 with the plane of the girder being approximately 5 per 
cent, greater than that for normal incidence." 

The regulations relating to wind pressure on bridges have already been mentioned. 
In the L.C.C. (General Powers) Act, 1909, we find that : " For a roof the plane of 
which inclines upwards at a greater angle than twenty degrees with the horizontal the 
superimposed load (which shall for this puipose be deemed to include wind pressure) 
shall be estimated at twenty-eight pounds per squat e foot of sloping surface." Also, 
" All buildings shall be so designed as to resist safely a wind pressure in anv horizontal 
direction of not less than thirty pounds per square foot of the upper two-thirds of the 
surface of such building exposed to wind pressure." 

Turning to the proposed L.C.C. Regulations for Reinforced Concrete — which may 
some day come into force — it is stated, " For a roof the plane of which inclines upwards 
at a greater angle than twenty degrees with the horizontal the superimposed load, 
which shall for this purpose be deemed to include wind pressure and weight of snow 
and ice, shall be estimated at twenty-eight pounds per square foot of sloping surface on 
either side of such roof. 

n 2sl 



THE CONCRETE INSTITUTE. 



[CONCBEXEl 



"All buildings shali be so designed as to resist safely a wind pressure in any 
horizontal direction of not less than twenty pounds per square loot of the whole 
projected surface normal to the direction of the wind. 

" All structures or attachments whatsoever in connection with a building, including 
towers or other parts which extend above the i oof flat or gutter adjoining thereto, shall 
he so designed as to resist safely a wind pressure in any horizontal direction of net less 
than 40 II). per sq. ft. of the whole projected surface normal to the direction of the 
wind. " 

It is impossible to include the regulations of the foreign nations and at the same 
mne keep this paper within respectable limits, but those for the chief towns of the United 
States are of (special interest, because of the gteat height of some of the buildings. 

The principal wind regulations for the United States are summarised in the 
following table : — 



Horizontal Wind 

Pressure in lbs. per 

sq. ft. 



Allowable In- 
crease of 
Stress in Wind 



Town. 






Bracing and Remarks. 








Members Sub- 






Exposed 


Sheltered 


jected to 






Position 


Position 


Wind Loads. 






Per cent. 


Per cent. 


Per cent. 


New York 


\ 








Except those under 


Rochester 










100 ft. in height in 


Minneapolis 


1 








which the height 


Louisville 


30 


30 


50 




does not exceed four 


Atlanta 










times the average 


Newark 


J 








, width of base. 


Jersey City 


' 








25 lb. at tenth story 
less 2\ lb. for each 












Philadelphia 


\ 3o 


25 t 


30 




story lower and i\ 


Syracuse 


to ■ 


25 




lb. additional for 






35 > 






each story above to 








1 a maximum of 35 lb. 


Detroit 


30 


30 


25 


Baltimore 

Buffalo 


) 

1 30 


30 


none 


— 


Chicago 

San Francisco ... 


' 20 

> 


20 


50 


— 


St. Louis 


30 


30 


20 


— 


Seattle ... 


None sp 


crilicd 


50 1 


Boston ... 


Provision for 


wind bracing sli 


all be made wh 


ere necessary. 


Providence 


1 v 1 «-• 








Los Angeles 


No regulations 









The amount of published matter on this subject is considerable. An endeavour 
has been made to embody within this paper the reliable information that is of practical 
use. 



2^2 



> r lt>NMl?IRTK>NAl 
ICJSOIM.I.PIMC, — 



REINFORCED CONCRETE GALLhlRY. 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information -will be presented of neii> -works in course of 
construction or completed, and the examples selected -will be from all parts of the •world. 
It is not the intention to describe these <works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea -which served as a basis 
for the design.— ED. 



DESCRIPTION OF REINFORCED CONCRETE GALLERY AT THE EMPIRE 

THEATRE. WHITBY. 

Tins gallery, although not the largest constructed of its kind, is of particular interest 

on account of the long cantilevers employed to carry same. 

Upon reference to the plan, Fig. 2, it will be seen that the width of the gallery 

is 39 ft. and its mean depth about 33 ft. Between the front of the gallery and the 

front wall of the building there 
is a q-in. brick wall. 

Reference to the cross 
section, Fig. 3, will show how 
the position of this wall was 
taken advantage of to dispense 
with main beams by construct- 
ing two reinforced concret • 
columns in the thickness of 
the wall to carry the two can- 
tilevers shown in Fig. 2. 
These cantilevers have a 
length of 18 ft. 6 in. from 
centre of column to face of 
curb, and give a good idea of 
the possibilities of this com- 
bination of materials for con- 
structional work. 

The two front cantilevers 
are balanced by two canti- 
levers at the back of the gal- 
lery, which are anchored at 
their ends into the mass con- 
crete footings of the front 
wall, in order to prevent any 
rotating tendency of the front 
cantilevers when loaded first. 

The strip footing to the 
columns is 2 ft. wide by 18 ft. 
long. The beam to this foot- 
ing" is 3 ft. deep by 9 in. wide 
with toes on either side 6 in. 
thick. The columns are 9 in. 
by [6 in., stiffened by a 9 in. 
by q in. tie at the level of the 
underside of cantilevers. 

The cantilevers at th • 

Fig. 1. View of Finished Building. hick are 4 ft. h in. deep bv 

The Empire Theatre, Whitby. I2 hi. Wide, and those at the 




D 2 



2 53 



NEW WORKS IN CONCRETE. 



[CONCRETE] 



/ront taper from 4 ft. 6 in. deep at the columns to about 10 in. at the front, and are 
likewise 12 in. wide throughout. There is a curb round the front b in. bv 5 in., and 
over this the balustrade wall itself 3 in. thick. The stepping to the gallery has a 
tread of 30 in. and a rise of 7^ in. 

At the back of the gallery there is a distributing beam 18 in. bv 9 in., and each 
back cantilever has a member 8 in. by 8 in., which forms a cover to the anchor bars 
referred to before. 




Qnchorinq Ties 



Fig. 2. Plan. 
Ki::nforced Concrete Galllry, Empire Theatre Whitby. 

Fig. 4 is a photograph of the completed gallery, and Fig. 5 .a photograph of the 
underside of same, which clearly shows the 18 ft. 6 in. long cantilevers. 

The staircase leading to the gallery was also constructed in reinforced concrete. 
'I his structure was designed to carry an evenly distributed load of 1 cwt. per super- 
ficial foot (in addition to its own weight) with a factor of safety of four, and proved 
to be perfectly satisfactory when tested. 

The designs were prepared by the Indented Bar and Concrete Engineering Co., 
Ltd., of Westminster. The reinforcement was entirely of indented bars. 

The architect for 
the building was Mr. 
A. K. Young, 77, 
Baxtergate, Whitby. 
The work was car- 
ried out by Mr. John 
Cooke, of Hudders- 
lield, as contractor. 

Mass Concrete, to rVa/J ' fbotma. CONCRETE 

~~ * COTTAGES AT 

WROTHAM. 




The Wrotham Te- 
nants, Ltd. (('hair- 
man, Sir Mark Col- 
lett), have had some 

cottage-, buili at Battlefield, Wrotham, Kent, by the Concrete Block Company, Rams- 
den, Billericay, Essex. 



1 i Section. 

Reinforced Concrete Gallery.'Empire Theatre, Whitby. 



54 



j T OONM'PlKTlONAll 
A> N(.INKt-WlN(i — J 



REINFORCED CONCRETE GALLERY. 




Fig. 4. View of Completed Gallery. 




Fig. '5. View showing Underside of Gallery and the 18 ft. 6 in. Cantilevers. 
Reinforced Concrete Gallery, Empire Theatre, Whitby. 



*5* 



NEW WORKS IN CONCRETE. 



CONCRETE 



The estate is situated about one and a-half miles from Wrotham Station. 

Fourteen cottages in all (seven pairs) have so far been erected, and it is stated that 
they have proved very satisfactory; the erection of further cottages is, therefore, 
under consideration. 




On, pair of cottages was designed bj Mr. Arnold Mitchell, ami the cost of same 
is /'i;s each. The accommodation comprises two living rooms, 9 tt. 3 in. i>> ou. 3 -i 
and ,4 ft. s in. by 9 ft. , in.; :. scullery 8 ft. by 8 ft.; and there are three bedrooms 
measuring 11 ft. 3 in. by 8 ft., 7 ft by 8 ft. 9 in., and 15 ft. by 8 ft. 3 m. «S?^ v g;_ 

Two pairs were designed b) Messrs. Stanley Barretl and Driver. rhes( hav( 

256 



fj.C^ONMkMIC-llONAll 
^A. IVNOINM VINC. ^J 



CONCRETE COTTAGES AT WROTHAM, KI-NT 



worked oul .ii ^156 pei cottage, and the ground floor o\ each contains t w < * living 
rooms, i) ft. g in. b) g ft, and 12 ft. 9 in. 1>\ 12 ft.; further, a scullery, 8 ft. 6 in, b) 
s ft., and on the first floor there are three bedrooms measuring 15 ft. 9 in. by <) ft., 
9 ft. 1>\ 8 ft., and \i ft. bj 7 ft. 

Two pairs were designed bj Messrs. McDermol and ('<)., and cost ^183 each 

cottage. The accommodation here comprises two living rooms, 11 ft. bj io It. and 

11 ft. 9 in. 1>\ \\ ft. 11 in. respectively ; further, ;i scullery, 5 It. 6 in. by 7 ft., and 

three bedrooms of ili<' following dimensions : i<> ft. 9 in. by 9 ft., 10 ft. 2 in. by 8 ft., 

mil 13 ft. by 8 ft. <> in. 

The remaining two pairs were designed by Mr. Pinkerton ;m<l cost jC- u i 1) each 
cottage. These contain a living room, to ft. s in. by 10 ft. 43 in.; a kitchen, 12 ft. 
6 in. by 1 \ ft. 6 in. ; a passage, 5 ft. 9 in. by io ft. 8 in. ; a scullery, 4 ft. q in. by 
[2 ft.; ami three bedrooms, 10 ft. 8 in. by 13 ft., 11 ft. 3 in. by 8 ft., and <> ft. 6 in. 
by 10 ft. 

All the cottages were erected entirely of concrete. The outside walls were buill 
y)i q-in. hollow concrete blocks made on an American block machine and on a 
" Wingel " machine supplied by Messrs. WinJet, Ltd., of Newcastle-on-Tyne. The 
inner walls were built of concrete slabs made partly on a " Wingel " machine and 
partly on a " Perfection" machine, the latter being supplied by the Star Concrete 
Machinery Co., 8, Manor Park, Lewisham, S.K. 

The blocks and slabs were made on the site and consisted of three parts bfeez< , 
two parts sand, and one part cement. The outside walls were cement and lime 
rough cast. 

The ground floors ware finished with [-in. floor hoards nailed on direct to the 
pitched and tarred breeze concrete. 

All the cottages were roofed with red " Rec< rd " concrete tiles, also made on the 
site on a " Record " machine supplied by the Star Concrete Machinery Co. It in- 
stated that the low cost of the buildings was to some extent due to the use of th ise 
tiles, which are made of two or three parts clean sharp sand and one part cement. 
We are informed that they have proved waterproof and stormproof. 




Concrete Cottages, Wrotham, Kent. 



257 



NEW BOOKS. 



[CONCRETE} 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books tohich have appeared during the last few months. 



British Standard Specification for Portland 
Cement. (Report No. 12, Revised March, 
1915.1 

Published fcr the Engineering Standards Committee, 
Victoria Street, Westminster, S.W., by Messrs. 
Crosby Lockwood & Son. 7 Stationers' Hall Court, 
Ludgate Hill, E.C. Price 5s. net 

A new edition of the British Standard 
Specification for Portland Cement, one of 
the most widely adopted of the Reports 
issued by the Engineering Standards Com- 
mittee, has just appeared. The Sectional 
Committee on Cement, presided over by 
Sir William Matthews, K.C.M.G., was 
formed in 1903, and the first Report was 
approved by the Main Engineering Stan- 
dards Committee and issued in 1904. The 
specification has been revised from time 
to time with a view of improvement in the 
quality of the cement, and the new edition 
just published contains further important 
modifications. 

Increased fineness of grinding of cement 
has been legislated for — the maximum 
residue permitted on the 1S0- mesh and 
70- mesb being reduced to 14 per cent, and 
1 per cent, respectively — and the minimum 
tensile strength at 7 days of both neat 
cement and cement and sand has been 
raided to 450 and 200 lbs. per square in. 
respectively. The clauses dealing with the 
preparation of the briquettes have been 
amplified, the procedure being described 
in greater detail than has previously been 
the case. In the case of both neat cement 
briquettes and cemenl and sand briquettes 
ramming or hammering is expressly pro- 
hibited, but the wording of these clauses 
^till leav« s scope for wide differences of 
opinion as to the quantity of water to be 
used and the precise methods of filling the 
moulds. The fact that the cement is only 
required to be plastic "when filled into 

the moulds " Should enable gangers to 

avoid the low and irregular results which 
await those using too great a quanlil\ of 
water. 

The growth of tensile strength required 
at 28 days both for neal i enn nt and cemenl 
and sand is now obtained by an. ins of a 

formula in place of the fixed percentages 
which have been specified hitherto. The 

formula gives a progressive increase in- 



stead of the somewhat irregular steps of 
the method previously adopted, but has 
the effect of requiring a somewhat in- 
creased percentage of growth on the 
higher 7-day figures. In the case of the 
neat tests 30,000 would probably have been 
a more equitable factor than 40,000. 

With the view of making easier the de- 
termination of what constitutes a visible 
impression in the test for final setting time 
the Vicat needle for this test is provided 
with a fixed metal circular cutting edge 
set half a millimetre back from the point, 
as this length is sufficient to clear the 
scum which sometimes forms on the sur- 
face of the pat. The cement is considered 
to be finally set when the needle makes an 
impression on the pat and the attachment 
fails to do so. The attachment is illus- 
trated on the plate showing the Vicat 
needle. 

All the plates have been entirely re- 
drawn, and two new plates have been 
added to the specification, one dealing 
with a standard spatula for use in making 
up the cement and sand briquettes, and the 
other shows an improved form of specific 
gravity bottle which the Committee have 
approved as suitable for use, though they 
do not stipulate for its employment to the 
exclusion of any other pattern. Instruc- 
tions for obtaining the specific gravity of 
cemenl are given on the plate. 

Spon's Architects' and Builders' PocKet 
Price Book. 

Publishers : E. F. N. Spon. Ltd., 5" Haymarket, S.W. 
Price 2s. 6d. nee 

This price book is issued in a conve- 
nient size for pocket use. It is most valu- 
able as a reference book to architects, 
surveyors, and others interested in the 
building trade or its various branches. It 
has been brought up to date, and contains 
a great amount of new matter. 

Extensive revisions have been made in 
the prices, which are in accordance with 
the cost of material at the time of going 
to press. 

The trades are in the order adopted in 

a well-drawn bill of quantities. Any in- 
formation required is easily found from the 

fullv detailed index tO the tildes. 



"V, eONM'PUCTIONAl} 
/vKNCilNKf.KlNli --J 



NEW hooks. 



Concrete Stone Manufacture. By Harvey 
Whipple. 

Detroit. Concrete-Cement Age Publishing Co, 253 pp, 
Price 11.00. 

Contents. The Development ot Concrete 
Building I nits Location, Equip- 
ment, Layout Materials, Mixtures, 
Manipulation Curing Special 

Moulds and Patterns Surfaces Shop 
Records and Cost Keeping Building 
Regulations rests Specifications- 
Selling the Products— Examples of 
Layout and Operation. 
The author of this volume deals with 

factory-made concrete units, which, as he 
states, have not developed as rapidly as 
field-made concrete in mass; although 
factory conditions are more easily con- 
trolled than field conditions. There is no 
doubt that there is some possibility of con- 
crete unit construction becoming more 
general in the future, but this industry has 
been seriously hampered in the past by 
many who have taken up the business 
without sufficient capital or enterprise and 
have been satisfied to put on the market 
inferior articles of limited application 
which have been no recommendation to 
the building owner. If this type of con- 
struction is to make any real headway it 
must be possible to obtain first-class pro- 
ducts capable of extensive application by 
numerous standard types which do not 
impose too many restrictions on the user. 
Mr. Whipple fully appreciates these facts 
and he has endeavoured to help the indus- 
try bv the suggestions and advice contained 
in this book. In dealing with the question 
of location, he gives the two important 
considerations which must be taken into 
account, viz., (i) The market for the pro- 
duct; (2) the availability of suitable raw- 
materials; and he follows this section with 
details of the equipment and methods 
necessary to produce good material. Manx 
drawings and photographs are given which 
enable the reader thoroughly to under- 
stand every point. The materials em- 
ployed are then described, and this is fol- 
lowed by an important chapter on curing, 
which contains much valuable information, 
and we cannot speak too highly of this 
section. In the chapter devoted to surface 
treatment the author is verv frank in his 



statements as to the lack ot beaut) in 
concrete blocks and units, but at the same 
time In- calls upon manufacturers to 
eliminate this disadvantage in the future, 
and suppoi ts his ( all \\ ith man) pi a< ti< al 
suggestions as to the attainment ot the 

object, and the illustrations given of work 
actually executed, where the appearance 

has been fully Considered, certainly indi- 
cate greal possibilities. After dealing with 
questions of obtaining good work of all 
(lasses, the fact that the manufacturer 
must make profits and build up a lucrative 
business is not overlooked, and this aspect 
is considered on practical lines by the 
author, who displays a thorough know- 
ledge of the whole subject. The book is 
well written, and is a comprehensive 
treatise on concrete block construction 
which can be thoroughly recommended. 

The Ternary System CaO-ALOr,— SiO . By 
G. A. RanKin. With Optical Study by 
Fred E. Wright. 

The American Journal of Science. 79 pp. 

Contents.— Introduction — Review of the 
Binary Systems — Phase Rule and its 
Application to Ternary Systems- 
Experimental Methods— Experimental 
Investigation — Recapitulation : The 
Concentration — Temperature Model 
Some General Considerations — Appli- 
cation of the Equilibrium Diagram. to 
Problems Involving the Three Oxides 
— Summary. 

This is an extremely scientific little 
book, which will necessitate some scientific 
knowledge on the part of the reader if he 
is to make an intelligent study of the 
matter contained therein. It is the first 
complete attempt to determine all the com- 
pounds, both binary and ternary, made up 
only of CaO, A1 9 0' 3 , SiO, and the mutual 
relations of these Compounds; and the 
investigations, of which this book is the 
record, necessitated some 7,000 heat treat- 
ments and subsequent optical examina- 
tions of the products. The data obtained 
are made use of in a discussion of the 
nature and constitution of Portland cement 
clinker, but, although the matter is well 
expressed and the diagrams are good, the 
book does not appear likely to be of much 
service to engineers generally. 



259 



IXDUSTRIAL NOTES. 



(CONCR ETE) 



INDUSTRIAL NOTES, 

These pages have been reserved for the presentation of articles and notes on proprietary 
materials or systems of construction put forward by firms interested in their application. With 
the advent of methods of construction requiring considerable skill in design and supervision, 
many firms nowadays command the services of specialists ivhose vieivs merit most careful 
attention. In these columns such vieivs will often be presented in favour of different 
specialities. They must be read as ex parte statements — ivith ivhich this journal is in no way 
associated, either for or against— but ive wou Id commend them to our readers as arguments by 
parties who are as a rule thoroughly conversant ivith the particular industry ivith ivhich they 
are associated. — ED. 



STEEL PILING. 

In recent years the Dock and Harbour Hoards have made considerable use of steel 
piling in carrying out extensions or new works. 

Among the more recent examples of the employment of steel piling is the work at 
the West Hartlepool Docks, carried out by the North Eastern Railway, under the Chief 
Engineer for Docks to that Company, Mr. Chas. Watson, of Hull. The scheme com- 
prises the modernisation of the North Basin with its entrances from the Old Harbour 
and the Central Dock. 

The old walls, with curved faces, will be replaced by vertical walls in concrete faced 
with blue brick and Cornish granite, the depth of water will be increased, and the 
entrances widened from 60 ft. to 70 ft. 

To effect this it was necessary to construct (wo large external cofferdams, one 
about 420 ft. linear at the Old Harbour entrance, the other about 230 ft. linear at 
the Central Dock entrance, as shown in Figs. 1 and 2, and the following conditions 
had to be met, involving much forethought and skill on the part of the North 
Eastern Railway Dock engineers: — 

The depth of water in the Outer Harbour is 33 to 35 ft. at high tide, with over 
16 ft. rise and fall, and north-east gales are prevalent in winter. Further, to secure 
sufficient depth for excavating the foundations of the new dock entrances, it was 











Fiji- 1. Showing Steel Piling Cofferdam at Old Harbour Entrance. 



260 



1 



, OONyiVUCTIONAL 
KNdlNtl RIMi — 



INDUSTRIAL NOTES 



necessan to penetrate ver) deeply, in some cases as much as 30 ft., into hard bouldei 

clay. 

These conditions involved the use of piling in 50-fl i<> 60-ft. lengths, and capable <»| 

withstanding exceptional!) heavj driving. 

After careful enquiries and inspection, the steel piling supplied b) the Side Groove 
Steel Piling Suppl) Co., Ltd. (Annison's Patent) was selected. It has a strong inter- 
lock, wide centres, ;incl .111 independent pile bar which can be Carried down ;is :i king 

pile below the sheeting members. (See Fig. 3.) 

The transport of these 60-ft. lengths presented slight difficulties, easily overcome, 
however, by the use of bolster wagons. 




Fig. 2. Steel Piling Coffkrdam at Central D(ck Entrance. 




Fig. 3. 



Fig. 4. 



261 



INDUSTRIAL NOTES. 



ICONCREXFJ 







* 



Fig. 5. 60 ft. Whole-Length Bent Corner Pieces. 




Driving 



Vvhole-Lbnoth Assembled Pile 1'<ai< 
and Shbbi img as One. 



In this connection, it is 
stated that in a few instances 
where deflection of the sheeting- 
members had occurred during 
transport, this was quite removed 
by the assembling. 

For cases where such lengths 
cannot be transported shorter 
lengths are used, the lengths 
being carried beyond the butts of 
the oval bulb sheeting-members, 
forming a sleeve-joint of great 
strength, the sheeting being fish- 
plated. (See Fig. 4.) 

In driving the two sections, 
a pile bar and sheeting-member 
being assembled by sliding the 
oval-bulb of the latter into one 
groove of the pile bar, the two 
were lifted together and driven 
as one, the free groove of tin- 
pile bar passing over the bulb of 
the sheeting-member previously 
driven thus (Fig. ()) effecting 
2\'l in. linear of work each time 
the piling machine was placed in 
position. 

The 60-ft. whole-length 
corner pieces were bent to the 
required radius, the assembled 
sections engaging and driving 
freely, and the penetration of the 



262 



'i», OONMU'WCTIONAl 
UtMilNKIl'INf. ^, 



INDUSTRIAL NOTES 



piling into Lhe extremel) hard N > * >i 1 1 1 East Coast Bouldei ( la} from 25 to as much as 
32 ft. was mos1 successful, the piling well sustaining the hard driving experienced. 

Fig. 7 shows the completed Old fiarbour Entrance cofferdam pumped out, and 
gives .1 good idea of its condition. 

Full particulars of the steel piling here described can !><• obtained from the Side 
Groove Steel Piling S 11 1 >j >1 \ Co., Ltd., t6, Water Lane, Great Tower Street, London, 
E.C., who are shortl) opening additional offices for the benefit of their man) Wesl End 
clients, in Victoria Street, S.W., as soon as the necessar) alterations are completed. 




Fig. 7. Shows Old Harbour Entrance with Completed 450-ton Steel Piling Cofferdam. 



l6 3 



MEMORANDA 



[CONCRETE] 




MEMORANDA. 



A 7o» 



Memoranda and News Items are presented under this heading, ivUh occasional editorial 
comment. Authentic neii's "will be "welcome. — ED. 



Iron and Steel Institute. — The annual meeting of the Institute will be held, by 
kind permission, at the Institution of Civil Engineers, Great George Street, West- 
minster, on Thursday and Friday, May 13th and 14th, 19 15, commencing each day at 
10.30 o'clock a.m. In the event of Mr. Greiner being unable to attend, Mr. Arthur 
Cooper, LL.D. (immediate Past-President), will preside at the meeting. 

The council have decided that, on account of the War, it will be inadvisable to 
hold the annual dinner this year. 

It has been provisionally decided that the autumn meeting shall be held in London 
during the week ending September 25th. Further particulars of the arrangements will 
be announced in due course. 

The Institute of Arbitrators. - - Our attention has been called to the above 
Institute, which has been formed in London at the instance of members whose services 
are usually invoked for the purpose of acting as arbitrators in commercial matters, in 
references under partnership agreements, building and other trade contracts, with a 
view to their corporate association both for their own benefit and in tne interest of the 
general public. 

Among the objects of the Institute are the following : — 

(1) To support and protect the character, status, and interests of the pro- 
fession of arbitrator generally. 

(2) To afford means of communication between professional arbitrators on 
matters affecting their various interests. 

(3) To arrange periodical meetings for the reading of papers and the discussion 
of matters connected with the duties and responsibilities of arbitrators, etc. 
The annual subscription is jQ\ is. The members of council at present are Professor 

Henry Adams, M.Inst.C.E., Mr. Max Clarke, F.R.I. B.A., Mr. F. Malcolm Barr, 
M.S. A., and Mr. I. W. Bullen, F.L.A.A. The president and vice-president have not 
yet been nominated. 

Fuller particulars can be obtained from the secretary, Mr. I!. C. Emery, at the 
temporary offices of the Institute, 32, Old Jewry, E.C. 

Warrington Bridge. This bridge, regarding which we gave a short description 
some- time ago, has now been completed. It is built entirely in reinforced concrete on 
the Considere system, and forms an important connecting link between Lancashire 
and Cheshire. It has taken three years to build, and cost ^23,370. A commemorative 
tablet was affixed to the bridge, and this tablet was unveiled last month by the Mayor of 
Warrington, who stated thai the bridge was the second widest in Great Britain, and 
was onlv 2 ft. less than Westminster Bridge. It will be remembered thai it is So ft. 
across between the parapets, and has a clear space of [34 ft. 

The White City. The Government tenancy of the While City ended in April, 
and the exhibition authorities have, we understand, decided to use the property h>r 
factory accommodation, which is much needed at present. The buildings can be well 



ana easily adapted u>r ihi 



urpose. 

New Pennsylvania TJevator of Reinforced Concrete at Philadelphia. A large 
amount of American and Canadian wheat for export is hauled by the Pennsylvania 

264 



j CONMU'UC TlONAl 
( v KN( il N M KM NO — , 



MEMORANDA 



from connecting railroad lines reaching the western wheal bell and from Buffalo and 
Erie, where it is received from Lake steamers^ to Girard Poinl a! the mouth of the 
Schuylkill Rivei near Philadelphia. This grain is there loaded directlj on i" ocean- 
«>oin«j vessels or stored temporarily in the new reinforced concrete elevator whi< h was 
recently put into service, replacing an <>M frame elevator which had been in use aboul 
i hiii \ years. 

The plant consists in general of a track shed in which the grain is unloaded; a 
working-house in which it is elevated, weighed, and distributed; a set of 54 circular 
and 40 intermediate concrete storage tanks in which it may he held temporarilj ; a 
loading gallerj extending out over the pier; a drier house for the treatment of damp 
or hcaicd grain, and a transformer house in which the high voltage electric current 
received from the Philadelphia Electric Companies' lines is transformed for use in 
operating the elevator. The plans contemplate the extension of the storage bins, and 
the duplication o{ the track shed and working-house alongside the present layout. 

The loaded cars are received in a 12-track yard about 000 ft. long, which converges 
to six tracks about 800 ft. lone extending over the twelve unloading hoppers in the 
track shed to an 1 [-track load yard about 500 ft. long, The cars are pushed through 
to the load yard south of the track shed by a locomotive, and are pulled hack, as required 
for unloading, by a six-drum Webster car puller. After unloading, the cars are given 
a kick by the puller which starts them down the 2 per cent, grade to the main yard. 
A double set of crossovers, with double slip switches between the track shed and the 
yard, allows the empties from any unloading track to be- sent in on any yard track. 

The track shed consists of a reinforced concrete slab roof 120 ft. by 144 ft. in size, 
covering six unloading tracks spaced 20 ft. centre to centre, and supported at an 
elevation of 23 ft. 6 in. on the low side by rows of concrete columns between the tracks. 
Each of the six tracks passes over two unloading hoppers in the track shed into which 
the grain is dumped by Clark car shovel machines. The track hoppers are arranged 
in four transverse rows of three each, served bv four belt convevors in the basement 
below the hoppers. The unloading facilities are designed to handle 250 cars in ten hours. 

The working-house is a concrete building 62 ft. 6 in. by 94 ft. b in. adjacent to the 
track shed. It is 202 ft. b in. high, and contains a basement, first floor, working bins 
74 ft. 6 in. high, and a four-storey cupola. Each of the receiving conveyors dumps 
the grain into a steel boot tank, from which it is elevated by one of the four receiving 
legs to the top of the working-house at a maximum rate of 15,000 bushels per hour 
for each leg. All elevating legs are operated by rope drive from electric motors. 

The receiving legs empty into 2,000-bushel concrete garners at the level of the top 
floor in the cupola, which deliver the grain to 2,000-bushel hoppers on 60-ton standard 
scales. After weighing, the grain may be distributed to the storage bins, to the drier 
house or the separators, to a car for re-shipment, or to the working-house bins for 
loading on boats. 

Five belt conveyors on the bin floor carry grain from the working-house out over 
the storage tanks. If the distributing spout under any particular scale hopper will not 
reach the conveyor serving the bin which it is desired to fill, a reversible transfer belt 
just below the distributing floor may be used to transfer the grain to the proper con- 
veyor. Self-propelled trippers dump the grain from the conveyor belts into the desired 
tanks. 

Construction of Buildings and Tanks. — The Girard Point plant was made both 
fire-resisting and permanent by the use of concrete throughout. The few necessary 
windows have metal sash and wire glass, and the gutters and cornice are of galvanised 
iron. Great care was taken to secure a stable foundation, as the load to be- carried 
when the tanks are full is very great. The adopted design, involving a solid 4-ft. 
concrete slab on piles under the entire structure is conservative, but was considered 
justifiable under the circumstances. The surface soil at the site is black mud to a depth 
of about 50 ft., the underlying strata being sand and, still lower, gravel. More than 
5,000 yellow pine piles 60 ft. to 70 ft. long were driven on 2-ft. 3-in. centres under the 
working-house and storage bins and on 5-ft. centres under the track shed. These piles 
were designed to carry 16^ tons each, although tests showed that a load of 54 tons 
would not cause a perceptible settlement. 

The piles were cut off at the elevation of the bottom of the slab and earth was 
packed around their heads. After laying the lower q in. of the slabs over the pile heads, 

265 




»••■-•— 



/n^TCT/^T\I?TPl? ^constructional 





^ 



Widening Dove Bridge, Uttoxeter 



The contractor who used the piling wrote : — "I have been well satisfied 
with the piling." 

The Piling used was our " SIMPLEX," in 18 ft. lengths, 22 lbs. per sq. 
ft. Sufficient was supplied to do half the work : the piles were driven 
through the timber foundation grillage of old work with a No. 3 McKieman- 
Terry Hammer, and withdrawn with one of our " GRIPS " : then we 
repurchased the materials from the contractor. 



Weights of Piling on sale 
" Simplex" 
" Universal " 




22 to 27 lbs. per sq. ft. 
from 43 lbs. 



v'fer 




y r CX?N5n?UCT]ONAli MEMORANDA 



EMG1NKK-V1 



a six-ply ICIt and pitch waterproofing membrane was laid, on which the remainder of 
the 4-ft. slab was placed. This waterproofing membrane was carried up the outside 
of the walls well above high-water leve) ami was protected l>> .1 single course brick 
wall laid in cement. The slab under the working-house was reinforced by J-in. bai - 

laid parallel with both edges and also diagonally, < inssiiii; under the column footings. 

The intermediate columns supporting the bins and upper floors of the working- 

house are 4 ft. in diameter and spiral reinforcement. The diagonal girder system '>t 

supporting the working bins, which was developed by Messrs. James Stewart and Co. 

in moo, and has been adopted for several of the new elevators, was used. 

The storage tanks arc 15 ft. in inside diameter and 96 ft. high with 7-in. walk. 

They are supported on rectangular concrete piers resting on the continuous slab. The 

walls are reinforced with steel hoops and vertical rods. The total capacity of these 

Storage tanks, including interspaces, is as follows : — 

27 circular tanks at 12,900 bushels ... ... ... 348,300 bushels. 

27 circular tanks at 13,200 bushels ... ... ... 356,400 ,, 

24 interspaces at 3,400 bushels... ... ... ... 81,600 ,, 

16 interspaces at 3,200 bushels... ... ... ... 51,-200 ,, 

Total 837,500 

The tanks are covered by a concrete slab forming the floor of the cupola in which 
the conveyors from the working-house are located. The roof is a 5r>-in. concrete slab 
covered by a four-ply tar and felt coating. — The Railway Gazette. 

Concrete Surfaces. — When concrete surfaces are discoloured as a result of smoke, 
soot, and similar impurities, it is sometimes possible to remove the accumulation by 
applying naphtha. If this fails a light application of sand blast will entirely remove 
the discoloured surface. — Concrete-Cement Age. 

Acid Towers Built of Reinforced Concrete. — An acid tower group of reinforced 
concrete has just been completed for a large paper company at Erie, Pennsylvania. 
Four towers, 10 ft. by qq ft., set in a square, 15 ft. centre to centre, form the group, 
which is made a unit by a common foundation slab and a housing at the top embracing 
all four towers. The towers are lined with special tile laid in acid-proof mortar to resist 
attack from the acidulated liquor dripping through the stone filling of the towers. The 
footing slab is 32 ft. square by 6 ft. thick, its horizontal reinforcement is engaged by 
the vertical rods of the tower reinforcement anchoring the towers. The stack shells are 
9 in. thick with ^-in. vertical and f-in. rings of square twisted rods. The lowest tower 
section has 20 vertical bars in the circumference, but at the top these are decreased to 
12 bars. The rings are spaced 5 in. apart in the lower section and 20 in. apart in the 
top. 

The height is qg ft. from foundation to tower top. A floor over the towers carries 
a housing 25 ft. 4 in. square bv 7 ft. 6 in. high where rock is stored. Over the housing 
in turn is a water tank 11 ft. square by 3 ft. high. Walls and columns support the 
roof. — Engineering News. 

PROPOSED NEW WORKS. 

New Mill. — The Urban District Council propose constructing a reservoir of 
1,500,000 gallons capacity, in regard to which the Local Government Board are holding 
an enquirv. 

Windsor. — A scheme has been sanctioned by the Corporation for carrying six 
filters on a reinforced concrete raft resting on concrete piles. 

Selsey.— Tenders have been invited by the Selsey Water Co. for the construction 
of a water tower or reservoir of 50,000 gallons capacity upon piers forty feet above the 
ground level, to be constructed on the " Kahn " system of reinforced concrete. 

Doncaster. — The Doncaster Rural District Council are considering tenders for the 
extension of their existing reservoir at Barmborough from 40,000 to 120,000 gallons. 
The work is to be executed in reinforced concrete to the competing firm's designs. 

Midlothian A concrete storage tank and other works for the supply of water to 

the Gorebridge district is to be constructed by the Gala Water District Committee of the 
Midlothian County Council. 

e 207 



MEMORANDA 



CONCRETE] 



Haddington. — Tenders have recently been lodged with the Town Council of 
Haddington for a concrete storage tank of 450,000 gallons capacity. 

Pontypridd. — The Ystradyfodwg and Pontypridd Main Sewerage Board propose 
laying a cast iron pipe sewer on concrete piers in the River Rhondda at Hopkinstown. 

ACCEPTED TENDERS. 

The following tenders have recently been accepted : — 

Bury.— Extension to reinforced concrete wall at the Electricity Generating Station 
for the Corporation : Bolton Stone and Concrete Co. 

Keith.- — Construction of Cuthil reservoir for the Town Council : W. Cruickshank 
Broomhill Road, Keith. 

Hull. — Construction and maintenance of reinforced concrete service tank and water 
tower at Holderness for the Hull Corporation : T. Goates and Son, .£3,173. 

CONTRACTS OPEN. 

London. — Tenders are invited by H.M. Office of Works, to be in by May 10th, for 
the foundations and concrete retaining wall in connection with the new General Post 
Office, East. Specifications, etc., of the Secretary, H.M. Office of Works, Storey's 
Gate, London, S.W. Deposit, £1 is. 

Whitby. — The Royal National Life-boat Institution invite tenders for a timber- 
fiamed life-boat house and reinforced concrete substructure, slipway and approach at 
Whitby Harbour. Quantities, etc., of Messrs. Douglass, Lewis and Douglass, engi- 
neers,'^, Victoria Street, Westminster, S.W. Deposit, £\. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum ^-in. Steel Plate. 



The 1 VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 



The VICTORIA 

is built to last 

WRITE FOR CATALOGUE No. 29. 



THE 

T. L. SMITH Co. 

13, Victoria Street, S.W. 



268 



Plezse mention this Journal nvhen %i>rttir<j. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume X. No. 6. LONDON, JUNE, 1915. 

EDITORIAL NOTES. 



THE CONCRETE INSTITUTE. 
The Annual Meeting. 

The mosl interesting feature in connection with the Concrete Institute's Annual 
Meeting was the speech made by Mr. Cyril Cocking in acknowledging the 
Institute's medal, which was presented him for his undoubtedly excellent paper 
on Calculations for Steel Frame Buildings, of which an abstract was given in 
this journal some time ago. 

The points raised by Mr. Cocking in his speech are of the greatest impor- 
tance and value, and in our opinion the speech should be given prominence 
and publicity, and is therefore reproduced below. Mr. Cocking said : — 

There were two important aspects which to his mind required the urgent 
consideration of the Concrete Institute. The first was the question of education. 

TECHNICAL EDUCATION AND THE WAR. 

At the present time the cream of the manhood of our Empire was taking a 
very active part in the greatest conflict of nations that the world had seen, 
a war that was being waged with scientific instruments which reached the 
highest level of human invention and human investigation. They were fighting 
a nation which could boast the finest educational system in the world, and the 
question for them, as an engineering institution and an educational institution, 
was, should they be ready, when the war was over and the period of recupera- 
tion and reconstruction was upon them, to take and hold the foremost position 
among the civilised nations of the earth? Should they be in a position to send 
out competent engineers and competent draughtsmen to repair the damage the 
war had caused, and should they be able to capture Germany's engineering 
trade in addition and without prejudice to the building and engineering work 
which was always on hand in this country? That was a problem of supreme 
importance to them, because it appeared to him that the nation that was going to 
make good and win and maintain the upper hand would not necessarily be the 
one that would be victorious in the field of battle, but the nation that took the 
shortest time to recover from the war's ill effects. The nations of Europe at 
the present time were like sick men on a bed, and it was the man that got up 
first that was going to remain the strongest. This to him was a very important 
point. It would mean a further war for commercial and professional 
supremacy, and efficiency in the engineering profession was almost, if not 
entirely, a question of education. It was a matter of national importance that 
the education of the structural and constructional engineer should be placed 
upon a sound and up-to-date basis. Classes of instruction should be so 
arranged as to give the necessary continuity of purpose in order that the deplor- 
able wastage of students' time which now obtained might be avoided. It was 
b 269 



THE CONCRETE INSTITUTE. [CONCPEXE 



also necessary that the instruction given should be uniformly good, well 
prepared by the instructor, and easy ol assimilation and retention by the 
student. In that connection he suggested that steps he immediately taken by 
the Institute to inquire as to the ways and means whereby the educational 
system of the country, particularly with regard to structural engineering", could 
be impioved and extended in order to ensure that the British structural engi- 
neer should hold the supremacy in every quarter of the globe. There should 
also be means provided so that the best advice could be given to the student 
leaving the day-school to enable him to fit himself as a structural engineer in 
the shortest possible time. He was convinced that, if the Institute were to 
consider the education question as directly applied to their profession, and drew 
up a comprehensive and well-conceived scheme, the education authorities would 
come up to the scratch and see the thing through. The most important point 
was that it should be done at once. In a vear or two thev would be too late, 
because our enemies had the education that we lacked. 

QUALIFICATION FOR THE STRUCTURAL ENGINEER. 

The second question he desired to bring to their notice was the necessity 
of some qualification for the structural engineer. It seemed to him a curious 
anomaly that a structural draughtsman with a deficient theoretical training - 
and incomplete practical experience should be, and often was, allowed to design, 
without supervision, structures upon which the safety or the lives of his fellow- 
men depended, whereas in the medical profession a rigid training and a certi- 
cate of competency were required before a medico could commence to practise 
at ail. In the past he had designed the steehvork for theatres and other places 
of public assembly, and with only the most meagre supervision, at a time when 
he could not regard himself as fully competent, and yet the lives of people had 
been and were still dependent upon the accuracy of his calculations, theories, 
and details. Surely the structural engineer should be required to show some 
certificate of competency before he was allowed to design without supervision. 

.Mr. Hills, in his Paper, had stated that the erection of buildings should 
only be undertaken by properly qualified individuals. On this statement he 
was persuaded that they were all of one mind, but were they to wait until 
some appalling disaster took place in their midst before the importance of 
proper qualification was brought home to the man in the street and the respon- 
sible engineer? The question of responsibility was often confused. Some 
people would argue that, because a public building must be designed to the 
design of the distrid surveyor, the district surveyor took full responsibility, 
or il ;i design was supervised by a consulting engineer, the latter took the 
responsibility. Personally, he could not accept that view; to his mind the 
responsibility rested with the designer, whether his work were supervised and 
checked or not. I he designer who refused the responsibility of his own designs 
declared himself incompetent and unqualified. The question was, what should 
be the qualification of ;i Structural engineer? Thai was for the Institute to 
decide. There- should be ;i theoretical qualification and a practical qualifica- 
tion, but the one was useless without the other. Win should not the Concrete 

Institute issue certificates of competency to competenl men? They would be of 

estimable value, both to employer and employee, and, incidentally, to the dis- 
trict surveyor. His own personal view was that it would have been better for 
270 



P^jSlVS'tS 1 ^ T,,l ' : CONCRETE INSTITUTE, 

the engineering profession ii the [909 Act had never been promoted, l>ui an 
Art ol Parliament had been passed compelling structural engineers to register 
themselves and empowering the Concrete Institute, together with the other 

Institutions directly interested, to forYnulate rules to !><• observed, both in the 
design and carrying out ol reinfi reed concrete and steel structures; thai \\;ts, 
constituting their branch ol the engineering profession on a l>;isis similar to 
thai of the legal profession and the Law Society. He knew it was vers diffi- 
culi to draw a comparison, bul an Act like the [909 Ait did not encourage the 
professional man; it only encouraged the incompetent by giving him rules to 
work to of which he did not appreciate the value and importance; in fact, the 
whole aim, especially of the Reinforced Concrete Regulations, was to make a 
Building Act that they might call " fool-proof." The Act had recently improved 
design, but only up to a certain point; it did not allow for future improvement 
and economy, and it destroyed originality. Personally, he would much prefer 
that the engineer should be properly qualified and be allowed a free hand within 
reasonable limits. 

THE LONDON BUILDING ACTS. 

Mr. Hills undertook a very big task when he commenced to deal with the 
London Building Acts in the form of a paper before the Concrete Institute, 
and we consider that he accomplished his work well. The fourfold objects 
of the Act cover such a wide field that it is impossible to confine the clauses 
to a few simple requirements, and a certain amount of ambiguity is inseparable 
from an Act which is drawn up by lawyers in the necessary legal phraseology 
to prevent any possibility of evasion. 

As time passes, so new conditions and methods arise, and, in consequence, 
an extension of the Act is necessary in the form of some amendment or other, 
and the course of evolution is such that this state of affairs will continue 
indefinitely, and we can only deal with the difficulties by passing new Acts at 
intervals of so many years which will eliminate for the time being the disad- 
vantage of having- to consider several Acts instead of one complete set of 
By-laws and Regulations. 

The great difficulty which designers often have to face is the fact that 
the "letter" of the Act is rigidly administered while the "spirit" does not 
appear to have any value, and it is in this respect that it would be advisable 
to give district surveyors the power of using their discretion. Several instances 
could be given in support of this statement, but it is not necessary to prove 
what is a generally acknowledged fact. The point to be remembered is that 
every clause in the Act is, or should be, inserted to accomplish a definite object 
or prevent the possibility of a certain danger occurring, and the clauses are 
framed in such a manner that they will cover the worst possible condition if 
necessary. 

There are many instances, however, where such clauses do not applv in 
the spirit owing to conditions which render their application unnecessary, but 
they must be enforced as they are in the Act. In many cases an application 
can be made to the London County Council, who recognise the fairness of the 
application and give consent, but time and money are so wasted because such 
consent could not be given by the district surveyor. If such discretion were 
given to district surveyors, we have sufficient confidence in them to know that 

B 2 

2 - 1 



THE CONCRETE INSTITUTE. 



iCQNCCETEJ 



their powers would be wisely and justly used, and no concessions granted 
which would endanger their reputations. 

The wording- and arrangement of the Acts as at present existing- certainly 
require a little more than average intelligence, and to the desig-ner the Act often 
appears as a kind of trap in which he is never quite sure he will not get caught. 
He may wish to comply with the Act in every way, but every new scheme 
seems to arouse fresh sections, which were not considered applicable in pre- 
vious work, and in one district the surveyor will read the Act in one way and 
in another district a different interpretation will be put upon it. Such a state 
of affairs could easily be remedied by making the Act more defined, without 
detracting from its controlling power. We do think that the tendency in the 
later Amendment Acts has been to state the requirements more clearly, and in 
the event of a new Act being passed to embody all the existing By-laws we 
hope that this tendency will be followed to the extent of reconsidering the 
whole of the wording and arrangement of the 1894 Act. 

The discussion which followed the paper at the Concrete Institute was 
verv interesting, and in many cases the opinions were to the point and indica- 
tive of the right principles, and we hope that the fact of the subject having been 
raised at the Institute will result in improvements in the near future, and thus 
benefit will accrue to the building owner, designer, and distriot surveyor, none 
of whom can express satisfaction with the Acts as at present existing. 

THE MICROSCOPE IN THE STUDY OF CONCRETE. 

We publish this month the first of a series of six interesting articles by 
Mr. Nathan C. Johnson on " The Microscope in the Study and Investigation 
of Concrete," which first appeared in the Engineering Record of the United 
States. Generally speaking, it may be said that these articles support and 
strengthen the opinions, long held in this country by those who have made a 
special study of the subject, as to the essential points to be observed in the 
production of strong enduring concrete. Thus, in his second article Mr. 
Johnson says : — 

' In sea water construction especially it is probable that the delects which 
induce failure lie primarily not so much in the cement, providing cement of 
proper quality be used, as in the improper proportioning of aggregates, or in 
poor mixing, or in a combination of the two." 

This endorsement of the view which has been so often urged in these 
columns is of peculiar value in this instance, as Mr. Johnson has approached 
and examined the subject in a direction which we believe has not been 
investigated thoroughly in earlier researches. Apart, however, from the 
grading", proportioning", and mixing of concrete materials, a wide field lor 
discussion on the complex problem of the hydration of Portland cement is 
opened up bv these articles. We should like to see this phase of the question 
pursued furl her in relation to the fineness of grinding of the cement. As is 
well known, the cement manufacturers of this country have been pioneers in 

the very line grinding" of their product, and one cannot but feel more than ever 
convinced, after reading Mr. Johnson's articles, that in voluntarily saddling 
themselves with increased cost of manufacture in order to improve the quality 

of their product they have probably rendered our engineers a service ol the 
very highest value and importance. 

272 



y r OON>Tk>l JCTIONA 1 
<i UVK.INLl.KMNe. — 



EMPIRE AND INDIA HOUSES. 










EMPIRE AND INDIA 
HOUSES, KINGSWAY. 



■yv-"-y, 



^■L-*l~> 




By A. LAKEMAN, M.S.A. 

There are many features of architectural interest in the 
buildings here described, ivhich are of steel-frame construction. 
The reinforced concrete features are the staircase and floors. -ED. 



Some excellent business premises have been erected in Kingsway from the 
designs of Messrs. Trehearne and Norman, architects, and they furnish a good 
example of modern building- as regards planning - , detail, and construction. The 

site is situated at the junction of Aldwych and King-sway, and the scheme is 
divided into two blocks, that on the angle with return frontages to King-sway 
and Aldwych being - known as Empire House and the other, which has a 
frontage to King-sway only, has been named India House. The latter has a 
frontage of 90 ft., and the former has a width of 47 ft. 6 in. to Kingsway, 
34 ft. to Aldwych, and 60 ft. on the ang-le. A plan showing the arrangement 
of a typical floor is illustrated in Fig. 1, and it will be seen that the maximum 
of lighting- has been obtained by the introduction of suitable areas, and the 
staircases and lifts are situated in convenient positions, whilst allowing- the 
floor space to be divided up into offices when required without loss of room. 
Another point that is worthy of notice is the absence of internal columns or 
stanchions, which might prove to be obstructions in the economical division of 
the floor space, and in any case it is advantageous to have clear uninterrupted 
floors. There are eight floors above the ground floor and an additional floor 
in the coiner dome, while the basement floor is 12 ft. deep. The total height 
from the pavement to the main roof is about 104 ft., and to the roof of the dome 
about 125 ft., as shown in the section illustrated in Fig. 2. The elevation is 
illustrated in Fig. 3, and it affords an excellent example of the architectural 
treatment of a building which is intended solely for commercial purposes. It is 
obviously far more difficult to produce a fine architectural effect in a building 
of this class than in a monumental building, on account of the limitations placed 
iipcn the designer, and all the more credit is, therefore, due when a successful 
result is achieved, as in this instance. 

Owing to the omission of columns and stanchions, which would obstruct the 
clear floor space, the principal girders have rather long spans, and are, there- 
fore, of a fairly heavy section. In all cases the calculations have been based 
on the requirements of the London County Council contained in the 1909 Act, 
although the work to Empire House cannot be considered as that of a steel- 
framed structure, the walls conforming to the 1894 Act and not being wholly 
carried on steelwork at each floor level; but in India House thin walls were 
employed and the whole structure was designed as coming within the meaning 
of the Act applying to steel-framed buildings. The plan illustrated in Fig. 5 

shows the lav-out of the steelwork to Empire House at the first floor level and 

273 



EMPIRE AND INDIA HOUSES 



1CQNCBEXE3 





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EMPIRE AND INDIA HOUSES. 



this can be considered as a typical detail, The steel beams arc planned to 
divide th< floors up into bays about 12 ft, wide, and the span of these beams in 
nearh all cases is about 34 It., thus necessitating the use of compound sections, 




Fig. 2. Cross Section. 
Empire and India Houses, Kingsway, W.C. 

21 or 22 in. deep and 12 in. wide. The largest girders in the building- are those 
carrying the main front walls at the second floor level, these having a span 
of about 34 ft. and supporting two concentrated loads, each about 11 ft. from 
the ends, such loads being caused by compound steel stanchions which occur 

275 



EMPIRE AND INDIA HOUSES. 



OTCBETE] 






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EMPIRE AND INDIA HOUSES, 



1 a hind the puis seen in the front elevation extending through 1 1 1 * - second, 
ihirf!, and fourth floors. rhese l)^;nns are designed as box girders with ;i 
total depth al the centre ol \ ft. 6 in. and a width oi i ft. 9 in., and the) are 

built un with two 48 in. b) | in. web plates and six -' 1 in. b) ' in. flange plates 
.it top and bottom, connected to the web plates with <> in. by 6 in. by \ in. 
angles. Angle stiffeners are provided throughoul the length, and immediately 
undei t!u stanchions a length of <) in. by 5 in. rolled steel joist is placed 
verticalh between the two web plates. A detail of this work is illustrated in 
Fig. 6. The stanchions, with typical details of connections, is shown in Fig. 7, 
and it will be seen thai a grillage foundation was adopted. In the example 
shown three layers of steel joists were used, the top layer consisting ol four 
20 in. by 7.I in. joists 6 ft. <> in. long, resting on eighl 12 in. by 5 in. also 




Fi?<. 4. Interior View. 
Empire and India Houses, Kingsway, W.C. 



6 ft. 6 in. long-, and these in turn are bearing on nine 6 in. by 3 in. joists 
which are 8 ft. long'. The concrete below is 10 ft. sq. and this is carried up 
to the basement floor to envelop the steel entirely and prevent any corrosion 
occuiring. The steel base to the stanchion is kept 3 ft. below the floor line 
and is about 3 ft. 6 in. by 2 ft. 3 in., with the usual gusset plates and angle 
connections. The stanchion itself is of compound section and is built up with 
two 12 in. by 6 in. rolled steel joists and six 14 in. by 4 in. plates frcm the 
foundation to the first floor level, where the section is reduced by substituting 
four 14 in. by £ in. plates. 

The arrangement of the steel in the octagonal dome is shown in Fig. 8, 
this being built up with 15 in. by 5 in. rolled steel joists, which act as hips, 
attached to a plate ring \ in. thick, and over these and between them a 
reinforced concrete filling is placed, while radiating 6 in. by 3 in. R.S.J. 
are suspended from the hips, and these in turn carry 5 in. by 3 in. steel 

277 



EMPIRE AND INDIA HOUSES. 



[CONCRETE! 



joists, from which i^ in. by in. steel flat bars on edge are hung- with 
steel hangers to support the ceiling', which is executed with expanded metal 
and plaster. All the radiating' 6 in. by 3 in. R.S.J.'s are connected to a 
h in. centre piate, and four 2 in. by } in. steel flat suspenders are provided 
to hold them up, these suspenders being connected to the plate ring- above 
mentioned. 

The floors throughout are constructed with reinforced concrete slabs 
between the main steel beams above mentioned, these having spans of about 
12 ft. and being executed by the general contractor with ordinary round 




Fig, 5. Ground Floor Plan, showing anangement of first floor steelwork. 
j Empire and India Houses, Kingsway, W.C. 

rods of I in. and \ in. diameter, in accordance with drawings prepared by a 
' ompetenl engineer. 

'J he main staircase provided an interesting feature in the construction, 
this being carried out with round steel columns, cranked joist stringers, 
and reinforced concrete steps. The reinforced concrete work was executed 
with 6 in. and 5 in. landings with \ in. rods al about 6 in. centres and 
J in. distribution rods ;it 18 in. centres, and a minimum thickness of 5 in. 
was employed under the trend finishing, at the intersection of tread and riser, 
and rods parallel to the length of the flights were placed in both upper and 
lower surfaces of this concrete. The rods in the two surfaces were connected 

278 



f j r OONS rPlKTIONALl 



KM PIN!-: AND IN l)i A HOUSES, 







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Fig. 6. Empire House, Detail of Box Girder. 

Empire and India Houses, Kingsway, W.C 




CoAic^e-rci/o-o' 4*. 
Fig. 7. Typical Stanchion Detail. 



2-9 



EMPIRE AND INDIA HOUSES. 



ICQNCKETEi 



by wire binding" and the ends of all bars were hooked, some hooks passing 
over the flanges of the steel framing. It is interesting to note that the box 
girders in the building weigh about 12 tons eaeh, and approximately 000 tons 
of steel was used in the steel framing. 

A typical framing plan showing the lay-out of the steel beams and 
stanchions in India House is shown in Fig. 9, and it will be seen that 
the method employed is similar to that described for Empire House, with 
steel beams having fairly long spans, necessitating in many cases the 




4 • t Srtn .0- 



Fig. 8. Showing Detail of Dome Construction. 
Empire and India Houses, Kingsway, W.C 



use of compound sections. The bays are filled in with reinforced con- 
< rete slabs, the span in one case being nearly 18 ft. The main front 
in this building is also carried at the second floor level by box girders, 

two of which are employed, each with a span oJ about 35 It., and the 
girders have a total depth of 4 ft. 5 J in. and a width of 1 ft. 9 in. 
The section is built with two 48 in. by I in. web plates 10 in. apart and four 
21 in. by \ in. and one 21 in. by § in. flange plates, connected to the web with 
4 in. by 4 in. by \ in. angles. Two stanchions arc carried by this girder and 
280 



j.CONMINKTIONAI 
v UM(.lM.t-.KlN(. — 



EMPIRE AM) INDIA HOUSES, 



four angle stiffeners an provided below these and also at the ends where 
stanchions occur above the bearing area, and in the latter cases two shorl 
lengths oi 10 in. 1>\ s in. rolled steej joists arc placed between the web pit 
to transmit the load through the girder to the stanchion below. Intermediate 
stiffeners air also provided to the wdt plates, these being ol tee section. The 
stanchions used generally are compound sections built up with one or two 
rolled steel joists and one, two, or three plates to each flange, according to the 




Fig. 9. India House Framing Plan. 
Empire and India Holsks, Kingswav, W.C. 

load to be carried. Grillage foundations were employed, these consisting of 

two layers of rolled steel joists, a typical example being composed of three 

12 in. by 6 in. joists for the upper layer and ten io in. by 5 in. joists for the 

lower layer. In one instance on the ground and basement floors a solid steel 

column was used in lieu of a compound steel stanchion, and this was 10 in. 

diameter, and it extended in one length through the height of the two floors. 

The steel cap was t8 in. sq. and zh in. thick, and the base 2 ft. 6 in. sq. and 

281 



EMPIRE AND IXDIA HOUSES. 



ICQNCRErH 



_; in. thick, these being shrunk on to the shaft in the usual way. Connections 
at the intermediate floor level were required on both axes and on each side 
of the column, and these were arranged by providing' a cast steel ring in two 
pieces which was bolted in a sinking- ^ in. deep, specially turned in the column 
for the purpose. This ring was 7^ in. deep and it had a projecting flange 
3 in. wide to provide a seating for the beams, with stiffeners immediately below 
the centre of the latter, and, in addition, a h in. plate having a sliding 
fit to the shaft was introduced, to bolt the top flanges of the beams and 
hold them to the column. This forms a very good method of connection to 
a solid steel column and is much better than many of the types adopted by 
steel contractors. 

The general contractors for the two buildings were Messrs. Wm. Taylor 
and Co., Lower Mall, Hammersmith. The steelwork to Empire House was 
executed by Messrs. Powers and Deane, Ransome's, Ltd., Cubitt Town, and 
that to India House by Messrs. Archibald D. Dawnay and Son, Ltd., Batter- 
sea ; while the reinforced concrete staircase was carried cut by The Patent 
Impervious Stcne and Construction Co., Hammersmith. 




Fig. 10. Reinforced < "in r< U Staircase al Empire II* use 

1 -nil 1 am) India Hoi sis, Kingsway, W.c. 



2H2 



r 9. cttvs-rutrcTiOKA i \ 



ANNUAL GENERAL' MEETING. 




ANNUAL GENERAL 
MEETING. 



The Sixth Annual Meeting of the Concrete Institute took 
place on May oth, at Denison House, Vauxhall Bridge Road, 
ivhen the Annual Report was presented, Below toe give a Summary of the Report.— ED. 



A SUMMARY OF THE REPORT OF THE COUNCIL. 
Membership.— The Concrete Institute had on April 30th, [915, 935 Members, _(<> 

Associate Members, 8 Associates, 64 Students, 5 Special Subscribers, and 14 Honorary 
Members. 

There has not been considerable decrease in Membership owing to the war, although 
a number of Members of the Institute are serving with the Forces. Names of Members 
serving with the Forces of whom information has been received are recorded in a Rol' 
of Honour \\lu\h is given as an appendix to the Report. 

Finances.— In 1913 there was a deficit. In 1914 there has again been a deficit, 
but a smaller one, owing to an appeal by the former President, Mr. E. P. Wells, 
suggesting that Members should increase their subscriptions to the new rate of two 
guineas which was adopted when the total Membership of all classes had reached one 
thousand. The new subscription rates and entrance fees have also improved the income. 

Meetings. — The extra number of general meetings has been maintained, but in 
view of a number of the Junior Members joining the Forces, the Educational Lectures 
and the Informal Meetings of Junior Members were abandoned for this Session; such 
educational work will be resumed in the future. 

Award of Institute's Bronze Medal. — As the result of a ballot among Members 
of Council, the bronze medal for the best paper read in the 1913-14 Session has been 
awarded to Mr. W. Cvril Cocking for the paper entitled " Calculations and Details 
for Steel-frame Buildings from the Draughtsman's Standpoint." 

Scope of the Institute. — In the previous Annual Report reference was made to 
the enlargement of the scope of the Institute and the alterations to the Rules, which 
were approved at General Meetings. It was explained that alternative policies would 
be placed before a General Meeting for decision. This has been deferred until the war 
is concluded. 

The Institute and the L.C.C.— As regards the work of the Council and Com- 
mittees during the past year the chief business has been the further consideration of 
the Regulations proposed to be made under the provision of Section 23 of the Lcndon 
County Council (General Powers) Act, 1909, with respect to the construction of buildings 
wholly or partly of reinforced concrete. A revised draft of the proposed Regulations 
was received in September, and the Council and Committees in joint Session recon- 
sidered the matter, and made various recommendations for further amendment. It 
was found that the Institute's previous suggestions had been embodied in large part 
in the revised draft. 

Bills of Quantities. — A letter was addressed by the Quantity Surveyors' Associa- 
tion to the Commissioners of H.M. Office of Works and Public Buildings deprecating 

283 



THE CONCRETE INSTITUTE. [CONCRETE) 



the preparation by the Consulting Engineers (employed by the Department to make 
calculations and prepare drawings for reinforced concrete structures) of Hills of 
Ouantities upon which competing contractors based their tenders, and advocating the 
extension to such work of the present system, under which quantities for buildings 
erected in other materials were prepared by surveyors appointed by the Department. 
The Council of the Concrete Institute, together with the Quantity Surveyors' Com- 
mittee of the Surveyors' Institution, gave its support. The letter inquired whether a 
deputation from the three bodies in support of this suggestion would be received, but 
nothing has yet resulted. 

New Members of Council. — In June, 1914, Mr. J. S. E. de Vesian and Dr. J. S. 
Owens were co-opted as Members of Council. 

Nominations for Vacancies on other Committees. — The Engineering Standards 
Committee having asked the Institute to nominate a representative to take the place 
of Mr. W. G. Kirkaldv as representative of the Concrete. Institute on the Sectional 
Committee on Bridges and General Building Construction, the Council appointed Mr. 
R. H. Harry Stanger in that capacity. 

The Council also nominated Mr. H. Kempton Dyson, Secretary of the Concrete 
Institute, to fill the vacancy created by the death of Mr. Kirkaldv upon .the Joint 
Committee on Reinforced Concrete conducted by the Royal Institute of British 
Architects. 

The Institute's Examinations. — The Rules and Syllabus of the proposed examina- 
tion of the Concrete Institute were appended to the previous Report of the Council. 
The Council has decided that the first examination shall be held early in June, 19 16, 
of which due notice will be given. 

Members Deceased. — The Council regrets to record the decease of : — Hon. 
Members : Monsieur Armand Considere and Monsieur Edmond Coignet. Member, 
killed in action : Major A. H. Tyler, R.E., F.R.G.S. Member : Mr. F. Dare Clapham, 
F.R.I. B.A. 

Library. — Several donations to the Library have been received by the Council 
from authors, publishers, and kindred societies, and the Council expresses thanks to 
the donors. A list of books received is published from time to time in the Transactions. 

Finance and General Purposes Committee. — The Finance and General Purposes 
Committee has held regular meetings preliminary to each Council Meeting, and the 
general results of their deliberations are contained in the foregoing particulars of the 
Council's work for the year. 

Science Standing Committee. — In addition to considering the L.C.C. Regulations 
for Reinforced Concrete, the Science Standing Committee h;us been concerned, jointly 
with the Reinforced Concrete Practice Standing Committee, in the compilation of a 
Standard Specification for Reinforced Concrete Work which was submitted in draft for 
discussion at a General Mating. The Report has yet to be revised in the light of the 
discussion before it '.'in be rc-submitted to the Council for their final approval. 

The Science Standing Committee has the following matters under consideration :■ — 

1. Standardisation of joints arwl connections in reinforced concrete. 

2. Amendment oi tin- Standard Specification lor cement. 

3. Co-ordination of the Standard Specification lor structural steel of all kinds. 

4. The adhesion of and friction between concrete and steel. 

5. Reinforced concrete piles. 

(>. 'I he effect of sewage upon concrete. 
7. The effect of oils and fats on concrete. 

Reinforced Concrete Practice Standing Committee. — During tin past Session 

the Reinforced Concrete Practice Standing Committee has met, in conjunction with 

the other Standing Committees and the Council, to consider the L.C.C. Regulations 

for Reinfon ed ( Concrete. 

284 



1 



OONM'IMKTIONAl. 



ANNUAL GENERAL MEETING, 



The Committee has held joint meetings with delegates of the Quantit) Surveyors' 
Association and with Members of the Concrete Institute \\1h> are Quantit} Surv< 
l>\ profession. The Joint Committee in the previous Session submitted for discussion at 
.1 General Meeting a Draft Report on ;i Standard Method of Measurement for Rein- 
forced Concrete, During the past Session a number of meetings have been held for 
the purpose of revising this Report, delegates attending from the Royal Institute of 
British Architects, the Surveyors' Institution, the Institute of Builders, and the 
National Federation of Building Trades Employers of Great Britain and Ireland. As 
the outcome a final Report upon the Measurement of Reinforced Concrete in Building 
Construction was submitted to the Councils of the Concrete Institute and the 
Quantity Surveyors' Association and adopted by them. It has been arranged to con- 
tinue the work of the Committee with a view to the formulation of a Report on the 
Measurement of Reinforced Concrete in Engineering Works as distinct from Building 
Works. At the same time as the Draft Report above referred to was submitted for 
discussion, another Draft Report of the Reinforced Concrete Practice Standing Com- 
mittee alone was put forward. The work of revising this Report has now to be under- 
taken. The final Report will contain suggestions as to the manner in which engineers 
should furnish information to quantity surveyors, the nomenclature to be used, and a 
tabulated form for preparing quantities for reinforced concrete. 

The Committee has also been engaged jointly with the Science Standing Committee 
in the preparation of the Standard Specification for Reinforced Concrete as recorded 
above. 

The Reinforced Concrete Practice Standing Committee has the following matters 
under consideration : — 

i. Advice to clerks of works, inspectors, and foremen as to methods of properly execut- 
ing concrete and reinforced concrete work and of preventing defects and failures. 

2. Regulations, recommendations of joint committees, and various methods of calcula- 

tion in respect to the design of reinforced concrete and the like. 

3. Forms and centering for reinforced concrete work. 

4. Standard concrete mixtures for general purposes. 

5. The use of cinder, ash, clinker, and breeze in concrete. 

6. Means of keeping reinforcements in place when concreting. 

7. Methods of making concrete watertight and of waterproofing concrete. 

Tests Standing Committee. — The Tests Standing Committee has held joint 
meetings with the Council and the other Standing Committees, as previouslv 
mentioned. 

The Tests Standing Committee has the following matters under consideration : — 

1. The effect of the presence of sulphur and its compounds in aggregates. 

2. The grading of aggregates. 

3. The effect on concrete of physical changes: (1) Effect of temperature; (2) Effect of 

moisture contents 
\. The effect of the use of sodium silicate on the surface of concrete as affecting 
reinforcing metal. 

5. The erratic results obtained by the Vicat needle in ascertaining the initial setting 

time of cement. 

6. The collection of data regarding the elastic moduli of concrete for stresses within 

working limits. 

Parliamentary Standing Committee. — The Parliamentary Standing Committee 
has held joint meetings with the Council and the other Standing Committees, as. 
previouslv mentioned. 

It has the following matter under consideration :■ — The draft of a Bill promoted 
by the Society of Architects for the registration of architects. 

Investigation Committee. — The Investigation Committee has had under con- 
sideration reports of failures on reinforced concrete structures, but as the information 
c 285 



THE CONCRETE INSTITUTE. KOSCBEXE ) 

contributed was confidential, the results of their deliberations cannot be furnished in 
the form of a Report. 

Joint Committee on Loads on Highway Bridges.— The Joint Committee on 
Loads on Highway Bridges conducted by the Concrete Institute will shortly meet to 
consider their final draft Report. It is intended to be presented for discussion at a 
General Meeting next Session. 

THE ANNUAL GENERAL MEETING. 

The Annual General Meeting of the Institute was held at Denison House, Vaux- 
hall Bridge Road, S.W., with the President, Professor Henry Adams, in the chair. A 
short discussion followed the presentation of the Report, and of this discussion we 
give a summary below. 

A special feature of the meeting was the presentation of the Institute's medal 
to Mr. W. Cyril Cocking for his very excellent Paper entitled " Calculations and 
Details for Steel Frame Buildings from the Draughtsman's Point of View." 

DISCUSSION. 

The President, in moving the adoption of the Report and Accounts, observed that, 
in spite of all difficulties, the membership had not decreased, but had still continued 
to advance during the last three years. It was a matter for congratulation that there 
had not been a considerable decrease of membership owing to the war, although a 
number of members of the Institute were serving with the Forces. The Roll of 
Honour was not yet complete, and they would be glad to receive further information. 
The list of Papers read during the session had been the longest the Institute had 
ever had. As regarded the work of the Council in Committees, they would be glad 
to hear that the Reinforced Concrete Regulations of the London County Council had 
a i last passed through all their stages of revision, which had occupied some years, 
and were now in the hands of the Local Government Board and the London County 
Council for presentation to the Council and ultimately to the public. They were 
very well pleased with the result, and when they saw the document he thought the 
members of the Institute also would be satisfied. It did not profess to be perfect, 
but it was as perfect as the combined effort of all the various institutions concerned 
could make it, and the London County Council had met them in a very fair and 
friendly way with regard to their suggestions. 

As regarded the Balance Sheet and Expenditure Account, they would notice 
balance, being excess of expenditure over income, ^127 16s. 6d. They had put by 
a sum of ,£.150 towards their printing account for the next session because the printing 
had been somewhat delayed owing to the war. The printers said that so large a 
n Limber of their staff had joined the Forces that they were unable to use their ordi- 
nary expedition, but the Council had provided for that in their future accounts. 

The various Committees had been very active during the session. They had 
still in hand many items which would perhaps remain in hand for some time because 
they were gathering information, and if members could assist in any way in supplying 
information, the Council would be very glad indeed to receive it. 

Mr. Morgan E. Yeatman, M.A., M.Inst.C.E., seconded, and the motion having 
been put to the meeting, the Report and Balance Sheet were unanimously .adopted. 

PRESENTATION OF INSTITUTES MEDAL. 

The President said it was the custom to present the Medal of the Concrete Insti- 
tute to the author of the best Paper which had been read during the previous session. 
Where so many good Papers were received it was a matter of considerable difficulty 
to select one that was pre-eminent, but in the present instance he thought they would 
apee that the selected Paper was .in uncommonly good one. To members practis- 
ing in different branches different Papers would appeal in a different manner. The 
Paper by Mr. W. Cyril Cocking, entitled "Calculations and Details lor Steel-frame 

286 



g 



gEStSSiSgg ANNUAL GENERAL MEETING. 



Buildings from the Draughtsman's Standpoint," received the highest number of voti - 
ol the Council, and he had verj much pleasure in asking Mr. Cocking 's acceptance 
of the Institute's M< dal. (Cheei s. | 

Mr. \\ . Cyru Cocking, M.C.I., in accepting 1 1 1 < - honour, said he should treasure 
the Medal as a lively memory ol the privilege the) had accorded him in allowing 
him to address them, and the --till greater privilege of having his Paper discussed 
(here 1>\ engineers and authors who had been successful in attaining the highest 
positions iu their branch of the engineering profession. 

Me then went on to make a most interesting and important speech, the report 
of which will be found in our Editorial Notes on page -■<><)• 

Mr. IIi\k\ J. Tingle, M.Inst.C.E., M.C.I., proposed a vote of thanks to tin 
President for the arduous work he had carried out during the year on their behalf. 
Me headed the list of attendances at Council and Committee Meetings, and his work 
there was very valuable from his experience and tact. 

Mr. S. Bylander, Past President, J. I.E., M.C.I., in seconding, observed that the 
Council during the past year had carried through several important improvements as 
regarded rules, specifications, and other matters for the benefit of the profession, and 
he hoped that for many years the President would be able to had and guide them in 
the proper performance of their duties as constructional engineers. 

The resolution was unanimously adopted. 

The President, in acknowledging the compliment, said he did not take it so 
much as a -personal vote to himself for the small services he had been able to render 
as to the Council and the officers of the Institute. The work was not individual but 
collective, and in that its value consisted. 

The proceedings then terminated. 



C 2 287 



NATHAN C. JOHNSON 



[CONCRETE 




THE MICROSCOPE IN THE 

STUDY and INVESTIGATION 

OF CONCRETE. 



By NATHAN C. JOHNSON, 

Engineer of Tests, Raymond Concrete Pile Company, New York. 

The articles nvhich ive are reproducing on the use of the microscope in the study 0/ 
concrete are of considerable interest, but in reprinting them <we mould state that the opinions 
expressed are those of the author, and the Journal as such does not necessarily associate 
itself ivith the conclusions arrived at. The articles are reprinted by the courtesy of the 
44 Engineering Record," U.S.A., and the illustrations have been placed at our disposal by 
the author. — ED. 

The possibilities of the microscope as a tool for the concrete engineer— such is the 
keynote of the present series. In view of the service the microscope has rendered 
'■he metallurgist, it occurred to the writer that it would be equally valuable in dis- 
closing the real character of concrete. Concrete, no less than steel, is dependent for 
mass perfection upon the perfection of its smallest parts, and in no way so far known 
can the quality of these small components be so well, so quickly, and so accurately 
determined as by the use of the microscope. 

GENERAL CONSIDER- 
ATIONS. 

There is special reason, 
moreover, why every means 
for studying concrete should 
be investigated, for no other 
construction material to-day, 
not excepting steel, has so 
widespread a use and enjoys 
so great a popularity. Its 
possibilities are limitless. Its 
applications are numberless. 
Ik making and forming are 
<j f l h e simplest. Some 
roughly measured stone and 
sand from a convenient bank, 
a liti le < emenl from a near-by 
denier, some water, a little 
turning with shovels or by 
machine, a board form, and 
the trick is done. This is essentially true whether the work be greal or small. From 
an economic standpont, whether the economist be witting or unwitting, professional 
or lay, skilled or unskilled, educated or ignorant, such an appeal is irresistible. 

Bui desirable as ii is to have so easily made, so adaptable, and so cheap a 
material within the reach oi everyone, those very qualities have led to its abuse; 
and with abuse inevitably has come failure. It is a peculiaritv of Portland cement- 

2HX 




Fitf. l. Sandstone Grain magnified 40 diametera. 
The Microscope in the Study and Investigation oi Concrete. 



& 



CONM'UlKTIONAi; 
KN( .1 N EER1NG -— ; 



THE MICROSCOPE IN THE STUDY or CONCRETE, 



concrete thai a fair dtgn.' of mhkss is not prevented l»\ .1 great deal oi bad treat- 
ment in making, and 1l1.1t concrete made l>\ bad treatment looks almost as well 

at tin start as that which is properlj made. Ii takes time, oftentimes years, to 

reveal the hidden weakness, but time will surely bring it to light. There have been 

some unfortunate failures in 




J 




Fig. 2. Enlargement of Sandstone Grain shown in Fi^. 1. 
The Microscope in the Study and Investigation of Concrete. 



the past, luit there are more 
Id come in ill' 1 Inline, ;in<l 
these will give Portland 
cement and Portland cement- 
concrete an undeserved repu- 
tation for unreliability, unless 
it can be shown win these 
failures occur, how they may 
be prevented, and in what 
ways our present methods or 
materials must be changed 
to make concrete " as endur- 
ing as the living rock." 

USE OF MICROSCOPE. 

It will doubtless appear 
at first blush that the lack of 
homogeneity of concrete and 
the uncertainty of proportion- 
ing attendant upon usual methods of mixing and placing would make microscopical 
examination of little value, so far as actual construction operations are concerned, 
especially as the examination is made of samples of restricted size. The same objec- 
tion might be raised with equal justice in regard to the examination of steel. It is 
impossible to examine the whole of one ingot, or the whole of every ingot from each 
heat ; but by taking repre- 
sentative samples from each 
ingot, or from each bloom, 
and thus knowing the quality 
of the product, with this in- 
formation and a know ledge of 
the raw materials — the ore, 
or pig-iron, the flux, fuel, 
etc. — that entered into it, very 
close control is possible on 
huge-scale operations. 

It is the belief of the 
writer that the same will 
prove true of the microscopic 
examination o f concretes. 
The method is so simple, so 
direct, the results so indis- 
putable and convincing, that 
it should make a very power- 
ful appeal to everyone interested in the concrete industry. Nor is the apparatus 
required necessarily elaborate or expensive. It should further be remembered that in 
this work light is reflected from a single polished surface, which greatly simplifies 
the procedure. It is neither advisable nor necessary to grind down the section until 

289 




Fig. 3. Enlargement of Sandstone Grain shown in Fig. 1. 
The Microscope in the Study and Investigation of Concrete. 



NAT HAS C. JOHNSON 



[CONCRETE] 



light ran be transmitted through it, as has been required in most of the microscopic 
work done heretofore on cements and rocks. 

It is impossible, in a few lines, to do more than to indicate some of the possibili- 
ties of microscopic examination in concrete work — the quantitative analysis of con- 
cretes • the detection of impurities, such as vegetable, adhesive clay or other films 
on the sand or stone ; impuri- 
ties and adulterants in the ce- 
ment. Although this article 
and those following are not 
primarily intended as an ex- 
position of microscopic in- 
vestigation, a few illustration-, 
of such uses will be given and 
a few points touched upon 
which, it is hoped, will make 
a direct appeal to all who are 
interested in obtaining better 
con crete. It is hoped, also, 
that this appeal may prove 
general, and that microscopic 
examination will not be con- 
fined to the few whose names 
are already well known, but 
may soon find its way into 
every cement laboratory 
worth v of the name. 




Fig. 4. Concrete from'Wing Wall of Dam at Cornell University. 
The Microscope in the Study and Investigation of Concrete. 



PRELIMINARY CONSIDERATIONS. 

Before taking up the detailed study a review of what is well known in regard to the 
general nature of concretes and their making may prove of value. In this review it will 
simplify matters to put aside for the present all chemical questions in regard to the 
nature or the manufacture of cement and to assume that the cement is a perfect product 
which forms, when mixed with water, a sort of " mineral glue " which coats the sand 
grains and the stones so that they stick together. In other words, take the name at 
face value as " cement." 

There are four substances which enter essentially into concrete — stone (crushed 
stone or gravel), sand (either natural sand or crushed rock), cement, and water. 

These four substances are necessarily variables. Each has certain inherent pro- 
perties which musl be taken into account in forming the mass. If cement and 
water are considered as one substance — i.e., as a glue — the number of variables can 
be taken as three. What relation, then, do these substances bear one to another? 
And what function does each perform in the concrete? 

The first requisite in concret* i-^ strength, whether tensile, compressive or shear- 
ing. Th'- second requisite is density, but experience shows that density and strength 
.ire correlative. This is true of natural stones as well as of concretes (tests by R. L. 
Humphrey, Engineering and Mining Journal, June 20th, [902, page 921). Obviously, 
also, the strength of the composite product cannot exceed the strength and density of 
th'- strongest and densest of the materials. 

STRUCTURE OF STONE. 

Assume for convenience that sandstone is selected as the coarse aggregate and 
sand "f like nature ;is the line aggregate. Th'' structure of a sandstone sand grain, 



290 



rj T CONMPlKTIONAl 
[A. LN.IM 1 KM NO — 



THE MICROSCOPE IN THE STUDY OF CONCRETE 



as seen through the microscope, is shown in Fig. i. As a piece o! the coarse aggre- 
gate exhibits throughout an exactly similar structure, it is fair to take the ground 
th;ti all of ili<' pieces of stone that go into the concrete are built up o\ tin) particles 
in the same way. Further, ii i 1 ^ found thai any part <»l a larger m;iss ol the stone, 
Mich as ;> test cube, 'hows 1 1 1 « ■ same structure throughout as the sand grain, so thai 
the strength per unit area inherent in the sand grain should be the same as that 
inherent in ih«' test cube, which crushed al [2,200 H>. per square inch. Therefore, 
considering foi the sake of simplicity that :ill stresses in the concrete are compressive, 




Fig. 5. Photo-Micrograph of Mortar taken from Specimen shown in Fig. 4. 
The Microscope in the Study and Investigation of Concrete. 

if a concrete is made of this stone and this sand, any failure to withstand a crushing 
stress of 12,000 lb. per square inch must be ascribed either to the properties, the 
quality, or the improper use of the cementing material which holds the sand particles 
and the stone particles together, or else to the presence of some foreign substance in 
the matrix in which the particles are embedded. 

CONCRETE SHOULD APPROACH STONE IN DENSITY. 

It is axiomatic and also corollary to what has been before stated, that the more 
nearly a concrete approaches natural stone in density, th" better and more economical 

291 



NATHAN C. JOHNSON. [CDNCBEXE] 

will it be. If Fig. i is examined closely it will at once be seen that the sandstone 
sand grain is, of itself, ;i concrete, that it consists of tiny particles, closely compacted, 
held in place by, and filled between with, some cementitious substance, which is 
known to be either iron or silica, or both. Magnifying this same spot to a higher 
di gree, as in Figs. 2 and 3, the similarity between this natural and artificial concrete 
is made even clearer. Hut there is one marked difference, which is very evident — 
i.e., in natural stone the component particles are packed far more closely than are 
those of artificial concretes, and the cementitious layer between them is far thinner 
than the layer obtained by artificial means. This is a significant point and should be 
remembered. Considering a hypothetical case, assume that 1:2:4 sandstone con- 
crete in pure compression breaks at 2,200 lb. per square inch at a mature age, say 
one year. The cement alone should not crush below 8,500 lb. per square inch, nor 
the sand or stone below 12,200 lb. per square inch. To the eye the concrete appears 
perfect. Some tiny airholes may be visible, but these could hardly account for the 
comparatively low strength. The concrete may be struck with a hammer, or pulver- 
ised in a mortar, or analysed chemically, and the relatively low strength attributed 
to l< water-worn sand," or " dirty sand," or " poor cement," or any one of a hundred 
commonly-assigned possibilities. The problem is a serious one, for so far as the 
strength shown by tlie concrete is concerned, we might better have used shale, or 
some waste rock that would crush at not less than 2,200 lb. per square inch, instead 
of the expensive stone. Further, this strength of 2,200 lb. per square inch is in 
considerable excess of the average strength of concrete made under field conditions, 
so that, so far as concerns the strength of the product that is being turned out by 
hundreds of thousands of yards daily, an even poorer grade of stone might have 
been used, with a tremendous saving to contractor and owner in cost of aggregate. 
Extensive tests, however, would seem to disprove the correctness of the fore- 
going reasoning. Under certain conditions the ultimate strength of a concrete 
may equal the strength of the stone aggregate (Taylor and Thompson, Concrete 
Vlai)} and Reinforced, pages 391 and 392), though this is by no means true of all 
concretes. However, wide experience leads to the belief that a strong aggregate makes 
i\ strong concrete, and a weak aggregate a weak concrete. Theory and practice 
are seemingly antagonistic, but it may be that this established fact and the conclu- 
sions of the foregoing paragraph will after all be found to agree if the nature and 
structure of concretes be studied carefully. 

IDEAL IN PROPORTIONING. 

The theoretical ideal in proportioning materials for concrete is to approach maxi- 
mum density — i.e., the density of the large aggregate — by putting in just enough sand 
lo fill the spaces between the sioixs, and sufficient cement to coat over the entire 
surface of the stones and of the sand grains, as well as to fill the spaces between the 
sand grains. The exact volumes of these stone-voids and sand-voids are often deter- 
mined for practical work with the greatest care, but when concrete is proportioned on 
the b;isis of such determinations, something seems to go awry. The concrete does not 
show maximum density, as was planned; oftentimes far from it. Distrust of propor- 
tioning on the h,-isis of void determinations has been growing rapidly of recent years. 
Evidently, either the ideal is wrong, or the method of attaining it is poorly chosen. 

1' ma) help in understanding these millers to look at the inside of concrete o\ 
known composition, made by approved field methods. The specimen shown in 
Fig. 4 was taken from the wing wall of a dam at Ithaca, X.Y., this dam being part 
of the hydraulic power development of Cornell University in Fall Creek Gorge. 
Unusual care was taken in proportioning, mixing, and placing this concrete, in order 
lo have it water-tight, so thai the specimen may he considered a representative product 

of accepted field |>ra< I ii 1 . 
292 



[&F5ifNKV-Si"No^ THE MICROSCOPE IN THE STUDY OF C0NCRET1 

The specimen was prepared l»\ grinding until a smooth surface was obtained. 
As the plane of ihi^ surface would have laid about 8in. Irom the outer face "I 
the wing wall, its features should !»«• characteristic "I the entire structure. As is 
usual, when void determinations were made on this stone, ii was shaken down, in 
order to compact i( as closeh as possible. Evidently, in the present relative positions 




Fig. 6. Microscopic Traverse of Matrix of Concrete Specimen shown in Fig. 5. 
The Microscope in the Study and Investigation of Concrete. 

of the stones, the percentage of voids would be enormously increased. This would 
also be true, though to a less degree, even if the stones had not been shaken down. 
If this same increase of voids holds for the sand, the unreliabilty of void determina- 
tions as a basis of proportioning is readily understood. 

293 



NATHAN C. JOHNSON. [CONCRETE] 

AIR HOLES. 

Th« nexl most striking feature of this surface is the number and size of air 
holes visible. Some of them are very small, so small as to seem negligible; while 
others are of appreciable size. One or two lie directly adjacent to pieces of stone. 
If tlie surface were magnified a hundred times it would be a field 100 ft. on a side, 
with each stone a boulder and each air hole a cavern. Further, these large air voids 
(and the small ones as well) are of indefinite size and depth below the surface, so 
that conditions may be better, or may be worse, in other portions. Evidently, how- 
i ver, the matrix of sand and cement in which the stone is embedded is of uncertain 
texture. As this matrix is relied upon, not only to hold the stones together against 
disruptive stresses, but also to transmit compressive and other stresses from one 
stone to another (it being remembered that the stone has the greatest density and 
greatest strength of all the constituents of the mass), it is evident that some or all of 
these stones will be called upon to bridge air gaps of greater or less size and extent. 

It requires little or no imagination to picture the result of an application of stress 
to such a mass. Unless the large aggregate is very strong indeed, local failure must 
result at comparatively low unit stress values. Further, even if the large aggregate 
be very strong, low unit stresses on the mass may result in extremely high stresses 
on unsupported units, with local failure again resulting. One local failure brings 
other local failures, like a string of dominoes, until the whole mass gives way. It 
begins to be evident why rock of low strength cannot successfully be used as aggre- 
gate, unless conditions of mixing and placing are superior to those that obtained 
during the making of the wjng wall from which this sample was taken. 

Hut the tale has not yet been fully told. It has been seen that the matrix of sand 
and cement in which the stones are embedded has to transmit stresses. This being 
true, it follows that the sand grains, as components of that matrix, must each bear 
a share of such stresses. In the matrix of this specimen are they bearing the load 
of which they are inherently capable? Or must they, too, bridge crevasses and pits r 
as do the stone-,? The microscope gives the answer. 

CHARACTER AND STRUCTURE SAME THROUGHOUT MASS. 

Fig. 5 is an enlarged photo-micrograph showing a piece of the mortar taken from 
between the stones of the specimen shown in Fig. 4. This is a characteristic picture 
of the sand and cement matrix of the average concrete. The photograph was obtained 
by attaching a camera to the eye end of a microscope and enlarging the negative 
obtained, so that the field as seen by the eye is magnified about 25 diameters. In this 
way the large sand grains are seen as large as the pieces of stone used in the concrete, 
the small sand grains are of relatively large size, and minute holes, tot) small to be 
observed by the unaided eye, appear almost as caverns. 

Anyone not accustomed to microscopic work would be unwilling to believe that 
this figure was other than a direct photograph of a surfaced concrete. There is the 
same characteristic structure, the same "stones," the same wide separation of aggre- 
gate w hiili showed previously why void determinations on stone are unreliable as 
a basis of proportioning concrete. Bui perhaps the most puzzling of all are the dark 
masses and particles lying between the sand grains, too small to be sand and .also of 
a different colour. Investigation proves them to be unhydrated cement. If it has 
ever been wondered why il was possible to grind up a set concrete and obtain a re- 
set, thai wonder now disappears. 'Ibis unhydrated cement — often as much as 75 
per cent, of the amount used lies inert in the matrix, performing no function that 
mighl not he heller performed by as much line sand. Evidently the mixing lire- 
's are very inefficient. Nor is this an isolated case. No concrete that has yet 
come under the writer's observation fails to show a large percentage of unhydrated 
294 



i 



COMMINUTION A 1.1 
' KNClNhlKlNO — , 



THE MICROSCOPE IN THh: STUDY OF CONCRETE. 



cement. Some <>! thesa concretes are more than thirtj years <>Id, so that time 
cannot be said to be the sole determining factor in this regard. 

TRAVERSE OF THE MATRIX. 

fhe specimen ot mortar taken for this micro-examination was < ut at random 
from ih<' chunk shown in Fig. 4. Further, this specimen was surfaced at random, 
the surface thus obtained being polished with rouge to give proper relief to th<' various 
constituents. In area it did not exceel .', in. On a side, but the character of matrix 
found in this area is shown in the nine photographs »>f Fig. 6. Many more such 
photographs could have been obtained within this area, hut these nine should be 
sufficiently horrible examples. 

With a view to Illustrating the working theory before stated — i.e., assuming pure 
compressive stress and the bridging of air gaps by aggregate— these photographs have 
been arranged in such position as to make the effect of a vertical stress most evident. 
Each piece of aggregate in these pictures is a grain of sand, the magnification being 
about sixty diameters. .Many of these sand grams show in Fig. 5 as well, where 
they can readily be identified by their shape and their relation to other particles 
di termined. Air voids are readily distinguishable, as they show dead-black and 
structureless. 

In Fig. 6, View 1 shows a sandstone sand grain with an air gap along its lower 
sid< and half-wax around one end. Contact with matrix is had only on the upper 
sid< and at the end no! shown. 

View 2 shows a quart/ sand grain almost completely isolated by air gaps and 
surrounded on all sides by a honeycomb of air holes. 

View 3 shows a sandstone sand grain with a gap below and honeycomb matrix 
on all sides. 

View 4 shows, in an exceptionally beautiful photograph, a quartz sand grain in 
almost complete isolation. 

View 5 shows the large air hole seen in Fig. 5. As a support to even the besl 
aggregate, its value may be questioned. 

View 6 shows a quartz sand grain in almost complete isolation. 

View 7 shows a limestone sand grain, with a crevasse below and a large air 
hole at the right-hand end. 

Mew 8 shows a large air hole and some smaller air holes in the cement matrix. 

View 9 shows an end of the quartz sand grain and the crevasse seen in View 6, 
with a large air hole below in the cement matrix. 

TESTIMONY OF THE PHOTOGRAPHS. 

Evidently, from the testimony of these photographs, the cement of concrete not 
only does not coat the sand and the stone, so that they will stick together, but the 
sand does not closely fill in between the stones so that they will have proper support. 
Further, the cement does not fill in between the sand grains, so that they, in turn, 
will be firmly bedded and be able to withstand the load. Instead of a compact sub- 
stance, then, concrete is a spongy mass, from one-eighth to one-quarter of which is 
commonly air and water voids. Vet this specimen under examination was carefully 
made and placed. What careless field conditions produce is a question worth 
investigation. 

If the steel sold for structural purposes were as spongy and of as uncertain 
texture as the average structural concrete, steel structural work would be twenty 
years behind the present mark. The unwisdom of using great masses of any mate- 
rial of low and uncertain strength, in place of smaller sections of proper strength, 
needs no demonstration. 

Vet, if it were desired to aerate thoroughly any fluid, or semi-fluid, substance* 

29S 



NATHAN C. JOHNSON. [CQNCBETEJ 

no better means could be devised than the present systems of mixing concrete by 
agitating, churning, and pouring, with oftentimes a drop from a considerable height 
into the form to make undesirable assurance doubly sure. 

SUMMARY. 

Summarising the previous discussion, it should be noted : 

i. That the strength and density of concrete are in direct ratio one to another; 
and that for economic reasons, both direct and indirect, concrete should approach the 
density of natural stone. 

2. That the strength and density of any concrete have, as upper limits, the 
strength and density of the strongest component, usually the coarse aggregate. 

3. That the strength and density of any concrete are actually limited by the 
strength and density of the weakest component, usually the cement matrix. 

4. That the cement matrix is not worked at its maximum efficiency, largely 
because of air and water voids in the mass. 

5. That only a small percentage of the cement is hydrated, so that it can perform 
an active function, the remainder lying inert. 

6. That this relatively small percentage of active cement is to a large extent 
prevented from performing its function of bonding with the aggregate by intrusive 
films or bubbles of air. 

7. That the pieces of large aggregate and the particles of small aggregate in a 
concrete are in direct ratio one to another at distances approximately equally great, 
relative to their size; that they are not closely compacted after mixing, as they were 
when dry, so that void determinations are practically valueless as a basis of pro- 
portioning. 

8. That because of this wide separation of both large and small aggregate, 
because of the imperfect contact between cement and aggregate, and because of the 
weakness of the cement matrix in which the aggregates are embedded, costly aggre- 
gate of superior strength must be used, instead of cheap aggregate of a strength 
equal to the strength of the cement matrix, in order that these weak spots may be 
bridged and progressive local failure prevented at low unit stresses. 

9. That even with the very best of materials only concrete of inferior strength is 
commonly produced. 

10. That present methods of mixing tend to aggravate these undesirable condi- 
tions. 

The preceding discussion has dealt with certain defects in concrete due to 
entrapped air, but it should not by any means be assumed that entrapped air is the 
cause of all weak or defective concrete. 

On the other hand, it should not be assumed that those weaknesses already 
pointed out are the only ones traceable directly to that cause. Secondary ills follow 
the primary weakness in an almost bewildering sequence; and in subsequent papers 
on microscopi( study, which will appeal- in these columns, an endeavour will be made 
to touch upon a few of the most important and to indicate means for overcoming them. 

The work described in these articles was first undertaken about three years ago 
at Sibley College, Cornell University; and during the past year has been prosecuted 
under an Industrial Fellowship established by the Raymond Concrete Pile Company. 
'I he writer takes this occasion to acknowledge his indebtedness to the officers and 
stafl of Sibley College and other colleges of the university, both for permitting exten- 
sive use of apparatus and equipment and for personal encouragement and advice. 
The author also extends his thanks to the many individuals throughout the country 

who have responded, at much trouble to themselves, to requests for samples of con- 
crete from various structures, without which this research would have been greatly 
restricted. 

296 



», CONM IM)CI lONAU 
4 t.NC.lNhl-.mNti —J 



77//i LONDON BUILDING ACTS, 



1 " fi r * ^ V* 



ux n 




RECENT VIEWS ON 
I CONCRETE AND REIN- 
; FORCED CONCRETE. 



THE CONCRETE INSTITUTE. 



J 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. — ED. 



THE CONCRETE INSTITUTE. 

THE LONDON BUILDING ACTS, WITH 
SOME SUGGESTED AMENDMENTS 

By OSBORN C. HILLS, F.R.I. B.A., District Surveyor for the Strand. 



The following is an Abstract from a Paper read at the fifty-ninth ordinary general 

meeting of the Concrete Institute. A lengthy discussion followed, and was continued 

at subsequent meetings, and we also give a short report of this discussion. 
This Paper is submitted with the view and the hope that a new Act will shortly be 
prepared embodying the existing Laws, By-laws, and Regulations. In 1894 our present 
London Building Act was passed, and thereby cancelled some thirteen existing Acts 
which had to be read together. Twenty-one years have elapsed since then ; many 
decisions have been given in the High Courts, some of which completely annul the 
intention of the Act; many amendments have been framed, some of which have become 
law ; and it will soon be necessary to repeat the process of 1894 and pass a new Art 
embodying all the existing laws and regulations, with certain desired modifications and 
improvements. Such improvements should be the carefully-considered results of the 
various authorities : the Royal Institute of British Architects, the London Society, 
the Town Planning Association, architects, surveyors, structural engineers, builders, 
and property-owners should now unite in preparing such improvements in the Acts as 
they consider essential in readiness for submission to the proper authority. The London 
County Council " fathered " the Act of 1894 through Parliament, and the writer 
believes they have already collected much material for a proposed new Act. 

It is not suggested that the Concrete Institute should take the initiative in the 
matter, but, having already been recognised bv Parliament in the 1909 Amendment 
Act, it should be prepared at the right time to suggest such amendments as will conduce 
towards sound construction on economical lines. 

The Act should be clearly understood by all who read with average intelligence. 
It has to be administered by the London County Council and district surveyors. There 
are two important ways in which the Act needs amendment : (1) bv making clear 
certain ambiguous and faulty wording, or wording that has been the subject of 
ambiguous or unsatisfactory decisions; and (2) by adding to or deducting from the 
existing provisions and requirements. 

The chief objects of the Acts are fourfold : (1) To secure a proper width and direc- 
tion of streets ; (2) The sound construction of buildings ; (3) The diminution of danger 
arising from fire; and (4) The securing of more light, air and space round buildings. 

The author then summarised the existing Acts and made detailed suggestions for 
their improvement. 

The Paper then goes on to deal with the reinforced concrete regulations, and this 
part we give as follows : — 

297 



THE CONCRETE INSTITUTE. [CONCRET ED 

REINFORCED CONCRETE REGULATIONS. 

The Regulations of the London County Council with regard to reinforced concrete 
are divided into ten parts, as follows : — 

Part I. (General) describes the meaning of the term " reinforced concrete," speci- 
fies the application of the regulations and the nature of the materials to be used 
generally in reinforced concrete buildings, prohibits the use of any reinforcing metal 
for conducting electrical currents, and provides that copies of the plans and calculations, 
together with particulars of the materials to be used, are to be deposited with the 
district surveyor at the time when notice is served upon him under Part XIII. of the 
1894 Act. 

Part II. consists of data to be used for the purposes of the Regulations. It 
contains a list of superimposed loads to be allowed for on floors to be used for various 
purposes and roofs of different slopes. It requires provision to be made for wind 
pressure, and specifies the maximum allowable ratio of span to the depth of a beam 
or cantilever. It prescribes the bending moments to be allowed for in beams and slabs 
with various degrees of end fixing under different dispositions of loading. It specifies 
the maximum stresses to be allowed on concrete of various proportions, and in steel. 
It makes provision for anchoring the ends of all tensile and shear reinforcement, and 
specifies the modular ratio to be assumed in beams and pillars. 

Part III. (Beams and Slabs) contains regulations as to the minimum diameter 
and disposition of the steel reinforcement and the minimum thickness of slabs, and 
regulations as to notation and formulae to be used in calculating the resistance moment 
in beams and slabs. 

Part IV. relates to pillars and struts, and defines the terms " pillar " and " strut " 
and contains regulations as to the minimum and maximum diameter of reinforcing rods 
and their disposition and minimum area, regulations as to notation and formulas and 
tables to be used in calculating the permissible load with various degrees of end fixing. 
Part V. contains regulations as to walls, specifies the minimum thicknesses 
allowable, and the maximum area of openings permitted. It is to be noted that party 
walls and division walls are allowed to be constructed of reinforced concrete, and need 
not be of the thickness prescribed by the 1894 Act. 

This is a variation from the provisions of the 1909 Act in the case of steel-framed 
buildings, which require all party walls to be of the thickness prescribed by the 1894 Act. 
All brickwork, stonework, and plain concrete are required to be executed in Port- 
land cement and mortar, and the allowable pressures on brickwork so built are 
specified. No regulations are given as to the allowable pressure on stonework built 
in cement mortar. 

Part VI. contains regulations as to the allowable pressure on various beds of 
natural ground, and also limits the pressure on plain concrete in foundations. 

These are similar to the provisions of Section 22 (24) and (25) of the 1909 Act in 
the case of steel-framed buildings. 

Part VII. (Protection) contains regulations as to the minimum cover of concrete 
over the metal reinforcement. 

Part VIII. (Materials and lasting). This part contains regulations as to the 
quality, size, and proportions of the materials to be used for making concrete, with a 
table of the ultimate compressive stresses which must be attained for various propor- 
tions at the end of one month and four months after mixing. Regulations are also 
made as to the manner of mixing and placing the concrete. Nos. 165 to 167 give 
directions as to the quality and treatment of the metal reinforcement. 

No. 168 is printed amongst the regulations as to " steel," though it would 
apparently come better under the next set of regulations headed " Tests and Testing," 
which specify the maximum test loads to he applied ; such tests are not to be made 
within ninety days of the date of laying the concrete. 

PARI IX. contains regulations as to " Formwork or Centering." 
Pari X. relates principally to workmanship, providing that the work shall be 
carried on as continuously as possible, that it shall he protected from too rapid drying 
and from fro>t, and that concrete shall not he laid when the temperature is less than 
j d«-g. above freezing. 

No. [85 is a most essential regulation prohibiting the cutting away of concrete 
for pipes or any other purpose in such a manner as would reduce the strength of any 
pari of the structure below the standard set up l>\ the Regulations. 
298 



k 



coNswucnoHAq THE LONDON BUILDING At 



rh. remaining three regulations deal with woodwork, etc., fixed in 01 on the 
i oncrete. 

There docs not appear to be the same difficult) in determining whether the 
Regulations as to reinforced concrete will apply to a particular building as there is 
in determining whether a building is or is not a steel-framed building. Regulation 2 
states that "These regulations shall appl) only to the construction of buildings <>l 
reinforced concrete in which the loads and stresses arc transmitted through each store) 
to the foundations by a skeleton framework of reinforced concrete, or partly b) a 
skeleton framework of reinforced concrete and partly by a part) wall or party walls." 

Section 22 (29) of the [909 Act provides that " It shall be lawful to make an\ 
addition to, or alteration of, or to do any other work to, in, or upon a building in 
accordance with the provisions of that section, provided that the loads and stresses 
in the part of the building SO added or altered, etc. . . . are transmitted from the roof 
to the foundations by a skeleton framework of metal . . . and the provisions of this 
section shall in all respects apply to such part of a building as if the same wore a 
separate building." 

There appears to be no similar provision in the regulations, though from the 
wording of Clause 6 it appears to he contemplated that additions 01' alterations ma\ 
be carried out under the Regulations. In my opinion it would have been well to 
have inserted a similar clause to Section 22 (29). It would also have been better to 
make the Regulations applicable in all cases where reinforced concrete is used. In 
the present circumstances there would appear to be no regulation as to reinforced 
concrete floors in ordinary or steel-frame buildings. 

In the Regulations as originally drafted there was a provision similar to that 
in Section 22 (18) of the 1909 Act-viz., " In every building of the warehouse class 
a notice shall be permanently exhibited in a conspicuous place on each storey of such 
building stating the maximum superimposed load per square foot which may be carried 
on any part of the floor of such storey." This provision does not appear in the latest 
revision of the regulations. In my opinion such a regulation is even more desirable 
in the case of reinforced concrete than in the case of steel framing, because in the 
former it is impossible to ascertain by inspection the strength of a floor. 

Xo allowance is made for high-tension steel, so that apparently those systems 
which use mesh and other high-tension steel reinforcement would be inadmissible in 
buildings erected under these regulations. In the R.I.B.A. Second Report such steel 
is recognised, with a provision that the stress on it shall not exceed one-half the 
stress at the yield-point of the steel, and a maximum of 20,000 lb. per sq. in. 

It is also desirable to make a provision both under the Regulations as to reinforced 
concrete and in the Act as to steel-frame buildings that the drawings and calculations 
should be deposited with the district surveyor some time (at least one month) before 
the work is to be commenced. In the present circumstances, as notice is only 
necessary two days before the work is commenced, sufficient time is not given to the 
district surveyor to go through the scheme and check the loads which will come on 
the foundations before the foreman is clamouring at the door wanting the district 
surveyor to pass the bottoms for the stanchions and pillars. 

The regulations as to testing do not specify who is to require tests of the completed 
structure. Testing may be found necessary " by reason of any sign of weakness or 
faulty construction appearing." But the contractors' idea of " signs of faulty con- 
struction " may be very different from the district surveyor's. Who, then, is to 
decide? The New York regulations provide that "The contractor may be required to 
make load tests on any portion of a reinforced concrete structure within a reasonable 
time after execution." It is also noticeable that the New York regulations require 
the construction " to sustain safely a load of twice the superimposed load for which 
it was designed," whereas the London County Council Regulations limit the test 
load to ih times the superimposed load for which the construction was designed. 

The London County Council regulations as to protection are considerablv less 
stringent than the New York regulations. The latter require a minimum cover of 
2 in. of concrete in columns and girders, 1^ in. in walls and beams, and 1 in. in floor 
slabs; the former only require i^.in. in pillars, 1 in. in beams, and £ in. in slabs. 

The allowable stresses in concrete of 1:2:4 mixture under London County 
Council Regulations and New York regulations are compared below : — 

299 





[CONCRETE! 


.c.c. 


NEW YORK. 


LBS 


. PER SO. IN. 


600 


650 


boo 


5O0 


60 


40 


IOO 


80 


60 


80 



THE CONCRETE INSTITUTE. 



Extreme fibre stress on concrete in compression ... 

Concrete in direct compression 

Shearing stress 

Adhesion stress when bars hooked at ends 

Adhesion stress, bars otherwise effectively anchored 

CONCLUSION. 

When I was asked to give a short paper on " the whole subject of the London 
Building Acts, including the Steel-frame Act and the Reinforced Concrete Regulations," 
I felt I was asked to do an impossibility. My paper is very far from dealing 
exhaustively with the subject, and I am fully alive to its shortcomings. I can only, 
however, submit it for what it is worth, and trust that the discussion to follow will 
bring out many useful suggestions for future amendments. 

DISCUSSION. 

The President {Professor Henry Adams, M.Inst. C.E., etc.) said that Building By-laws were 
a perennial source of discussion. There were perhaps no Regulations more difficult to make 
and none that gave so little satisfaction to those concerned in obeying them. From time to 
time the objectors fell into line, and modifications ensued. The time now appeared to be ripe 
for another general consolidation of the various Acts and Regulations, and this was a good 
opportunity to ventilate grievances. 

With regard to the footings for brick walls, under the London Building Act, it was worthy 
of note that in the North of England it was customary to> build without footings, although in 
the London Building Act they were told they were essential. The District Surveyors' fees on 
repairs sometimes exceeded the cost of the repairs themselves. In his own practice he made 
eight times the thickness the limit of projection — that was to say, a half -inch plate might 
project not more than four inches. That was the extreme, and the same rule applied to girders. 
Where there were two or more plates he should consider >: properly riveted" meant "tack 
rivets," not more than six inches pitch. He agreed with the Author as to the riveting in the 
base plates, but it was seldom that the base was machine planed before it was connected to 
the base plate, and that was why the whole stress must be capable of being taken by the rivet. 
With regard to riveting through a thickness of four or five inches, it was not so many years 
ago that there was no machine riveting, and good work was quite possible by hand through 
this thickness. All that was necessary was that the point should be cooled before the rivet was 
driven, so as to cause it to swell in the centre under the blows of the riveters. A notice should 
be permanently exhibited on every floor of a reinforced concrete warehouse, stating the 
maximum superimposed load for which the floor was designed. The Council of the Concrete 
Institute pressed for this Regulation, but the London County Council had no power to make it. 

Mr. H. D. Searles-Wood, F.R.I.B.A. : One of the great things they could do in a new 
building Act was to avoid the terrible delay which occurred in getting approvals from the 
London County Council. The thing was crystallised to such an extent that it ought not to be 
necessary to spend all the time they did in getting their plans passed. Surely it would be 
possible now to have a little more scientific treatment of the subject and not so many schedules. 
Lei the designer show that he had properly calculated his structure, and then give him a free 
hand. 

Mr. W. Cm. Perkins (District Surveyor for llolborn) observed that the present Acts undoubt- 
edly required to he amended and modified in order that they might be more easily understood 
by persons who were building in London, so as to admit of more recent improved and 
scientific methods of building being adopted freely and without the necessity of going to the 
Loudon fount;. Council lor special sanction in individual cases, lie was not sure that it was 
a good thing to give the district surveyors more discretion in the various eases that arose under 
'li<- Art. Sometimes ;i discretion was a two edged sword lie complained that the City was 
excluded from the law governing the general line of buildings. lie did not agree with Mr. 
Hills thai tie- district surveyor had unlimited discretion as to the interpretation of Section 78 of 

the 1804 Art. Hi, opinion was thai the district surveyor must see thai the whole of the rules 

0! ill-- A' 1 wrc complied with in the case of .1 public building, but he had power to ask lor 
anything further thai he though! necessary in the way of construction. 

Mr. E. Fiander Etchells, A.M. Inst. C.B., etc. : The clauses of any amended Ait OUghl to 
be drafted by architects and engineers to save them from the lawyer-drafted clauses which 
enabled th< n, under Section X of the Act of 18943 to lay out n street, provided they said thej 
were doing something < I ■ 
300 



t T O&NMkMKTIONAL 
v 1 NCINI 1 KMNC — ; 



THE LONDON BUILDING ACTS 



The publications of the Engineers 1 Standards Committee were frequently referred to in 
Aiis ol Parliament, and il might be an advantage to adopt .1 similar sugg< tion instead of 
incorporating schedules in the new Building Act. 

Mi- admitted thai th< re was .1 desire on the part oi all of them to remove anomal 1 

the present Building Act, but he cautioned them that anomalies could not be done awaj with 
altogether. The\ could onlj hope that the anomalies to come would not be 10 confusing and 
distracting .is some- of those to which their legal friends had alreadj subjected them. With 
regard to Building Laws in general, the idea of Building Law »^ that which was most in 
accordance with Natural Law, and in that he included Mechanics, Hygiene and Ethics, and 
also the true laws of sound finance in the highest acceptation of that term. 

He reminded the meeting that 7.000 dangerous structures were dealt with every year, and 
onlj one or two got Into the papers. Many of the criticisms should not be addressed to the 
building authority, because thej had endeavoured to find a compromise between extreme views; 
they should be addressed to other engineers who held these extreme views. "The gr< 
common measure of fads" wa^ brilliant as a phrase, but it did not compare with the actual 
facts. 

Mr. Wm. Woodward, F.R.I.B. 4., remarked that Mr. J fills took a reasonable view of the 
Building Acts. It was possible, however, for a District Surveyor to take such a hard and fast 
line in the administration of the Acts as really at times to make them very oppressive. He 
was old enough to remember the preliminary discussions to the Act of 1894. At that time 
those who were in authority in the London County Council desired to frame some of the 
sections in a confiscatory manner so as to have a dig at the ground landlords. The Building 
Act of iScj4 did sometimes interfere with the value of property, but, speaking personally, 
on the whole he thought it protected the public from many of the drawbacks and nuisances in 
existence before it was passed. They all hoped for a new Act which would contain in itself, 
without reference to other Acts, all that was necessary for carrying on the work of building 
in London. There was great difference of opinion amongst District Surveyors as to party 
walls, but his contention was that such a wall became an external wall beyond the height where 
it separated buildings. 

Mr. Edward Dru Drury, F.R.I.B. A. (District Surveyor for St. Margaret's, Westminster), 
reminded the meeting that, in a case of his against the Army and Navy Stores some years 
ago. the Court of King's Bench decided that a party wall ceased to be a party wall as soon as 
it reached 15 in. above the lowest building. When they had a new Act it would be important 
to have in it a definition of a division wall. 

Mr. C. S. Meik, M.Iast.C.E., referring to the manufacture of reinforced concrete, said it 
was useless to make very stringent provisions for the design of work unless some strict 
supervision was exercised over the carrying out of the work. The Local Government Board in 
their Regulations, it appeared to him, had done a great deal to discourage the introduction of 
reinforced concrete, and he hoped to live to see these Regulations and the County Council 
Regulations as to reinforced concrete very much improved and condensed. 

Mr. J. Ernest Fraack, A.R.I.B.A., disagreed with previous speakers, and thought the 
drafting of the new Act should be left to lawyers, who would bear in mind the continuity of 
the Act with the preceding Acts. The Act of 1894 put a premium on bad building. The new 
Act should be framed on broad principles and certain ratios should be given, which should be 
worked to. Under the i8g4 Act many brick walls were erected which should not be allowed, 
while in other cases they had to build a wall which was unnecessarily thick. 

Mr. Lawtoa R. Ford, A.R.I.B.A. (District Surveyor for St. James's, Westminster) : A con- 
solidated Act, with amendments doing away with discrepancies and various anomalies was one 
of the pressing needs of London, as great changes had taken place in building construction 
during the past twenty-one years. 

Mr. Percy Hunter, A.R.I.B.A. (District Surveyor for South Lambeth), maintained that, 
however much they consolidated their present Acts, there would be advances in building con- 
struction, and as far as he could make out, whatever Act they passed in any given year, ten 
years after they would want an Amending Act. If the principle of responsibility for his 
design were taken away from the architect they might as well abolish him altogether. One 
of the principles he laid down with regard to reinforced concrete construction was that there 
should be special supervision of the work. 

Mr. S. Bylander thought the responsibility should be shared between the designer and the 
builder. The law should be so amended that the engineer should accept responsibility for 
design. In order to simplify the design of a building next to another building, it would be 
advisable, where reinforced concrete was used, that plans showing the work as executed should 
be deposited with the London County Council, and architects should have the opportunity of 
examining these by paying a small fee, in the same way as company prospectuses were available 
at Somerset House. 

D 3 QI 



THE CONCRETE INSTITUTE. [CONCRETE] 

Mr. Allan Graham, A.R.I.B.A., expressed the opinion that the fruit of the paper would be 
not greater stringency, but greater leniency in connection with the Act. Everyone who attempted 
to alter or deal with the London Building Act ought to have an architectural training and 
understand the tremendous difficulties the architect had to face in complying with the regula- 
tions as regarded open space in a city like London, where ground was so expensive and where 
♦he regulations tied him up. He would much prefer to have the London Building Act, 1894, 
remain as it was than accept some of the suggestions which had been put forward. The whole 
tendency of regulations was to get worse and worse. Everyone had his fad, and they got the 
greatest common measure of fads as the result of all the deliberations incorporated in the 
by-laws. If there were one authority in London, as in Glasgow, an architect would come into 
his own and not be harassed by all these various troubles which hindered him in his profession. 
In Glasgow all charges were borne by the Corporation; a client had not to pay for the 
passing of his plans at all. 

Mr. Percy H. Simco dealt with that portion of the Act relating to s'.eel-frame buildings. 
This had been in many respects a useful Act, inasmuch as it had stopped by law all 
'' scamping" in steelwork in public buildings. But on the other hand, to those who had had 
to administer it and work under it, it had been somewhat a curse inasmuch as there was so 
much ambiguous wording in it. The building owner so far had had all the benefit. It would be 
as well that the architects of London should get their clients to make up their minds definitely 
before the plans were actually passed and the work put in hand. Clauses bearing on the actual 
engineering and constructional points ought to be drafted by those whose business it was to 
administer and work under the Acts, and then they might get some plain and straightforward 
wording. The Act should be on broad lines, and the district surveyors should be able in many 
instances to use their own judgment, because points were bound to crop up in construction 
which could not be covered by a cut-and-dried Act. In the event of any disagreement with the 
district surveyor, a tribunal of appeal should be set up, which should be easy of approach, 
and so delays could be avoided. 

Mr. W. Cyril Cocking thanked the district surveyors for the help they gave to engineers 
and architects in the design of public buildings. The value of a job had, to his knowledge, 
been increased 25 per cent, because of the kindness of the district surveyor in showing the 
architect how to do his work and how to get the best value out of his design. That was a work 
for which they got no remuneration whatever, and very little thanks. Architects should be 
compelled to notify the district surveyor of every alteration in the structure. It should be 
made part of the amendment of the London Building Act that all calculations, plans and 
details for uncompleted structures must be filed with the copy of the lease, so that when the 
job was completed the information would be at hand. All steelwork designed under the i8g4 
or the iQog Act should be submitted to the district surveyor for his approval in the interests 
of public safety. To him it was a pitiful sight to see a district surveyor poring over calculations. 
The district surveyor was much more wanted on the job to find out things that the engineer 
and the builder left out. Notices were not of much value; what was wanted was a periodical 
and surreptitious visit of the district surveyor. 

Mr. Ewart S. Andrews, B.Sc, considered that any rules made should not specify the 

ectiom beyond the beam, but the projection beyond the centre of the rivet. One of the 
chief difficulties arose from the allowable stresses being specified in the Act, apparently 
Intentionally, to drive them to deal with their stanchion as one with fixed ends. There was, he 
believed, no scientific justification whatever for the hinged end being reduced to the large 
extent it was on comparatively short lengths. The several stresses approached to a common 
value in a very short column, and the effect of the great reduction in the allowable stress on 
the hinged end- under the Acl was to drive people to have what they called fixed ends. If, mi 
the other hand, the figures were made more- lenient and more ill accordance with fact, hi* 
believed the difficulty would he solved to a very large extent. They should have some 
indication as to when an end was to he considered fixed, hut for that they would have to wait 
-•'in'- time. 'Ih'- number of rivets connecting tin- base plate to the main column really had to 

do with tie- question of fixity. If an end were perfectly fixed it would hear a very large 
bending moment before buckling would take place. As to the load on floors, he agreed that 
IOO was rather a high figure. Tie difficulty would he me! if the rule specified not only a super 
load, hut a ISO a eoneeiit rated load. 

Mr. H. Kempton Dyson, Secretary, Concrete [nstitute, said : Ten years ago, in a leader 

in the Builders' Journal lor April 5th, 1905, I wrote: '" It is important that the present Acts 

should he revised, and we consider the Council will he well advised not to wait longer than 

next year. We hopi- no half measures will he attempted, Inn that the old Acts will he repealed 

and a comprehensive new \it brought in, because the presenf Acts and amendments are quite 
confuting enough to professional men; a building ordinance should he businesslike in form. 

302 



^[^MpyrrioNAT^ THE LONDON BUILDING ACTS. 



Hitherto the suggestions of professional bodies have been treated with scan! court After 

receiving suggestions the Building; Act Committer should send theii altered clauses foi 
further suggestions, and not trj to rush through .1 Hill In defiance ''l -ill interested bod 1 

\, ,w the procedure adopted with and the form given to th< propo ed Reinforced Concrete 
Regulations conform most closelj to mj old ideals. The co-operation of the professional 
societies h .1 ^ been sought and then recommendations treated with courtesy, the al 1 
proposals have been senl again and again for further suggestions, while the fact that thej are 
to be Regulations and nol an Acl of Parliament will permit of their being revised and kept 
up-to-date. The language is straightforward and more intelligible than of old, Inn I ^iill 
await that desired complete overhauling of the existing Building Acts. The changes within 
recent years in the outlook on methods of constructing buildings point clearly to the advisa- 
bility of having the Building Ordinance in a form which can be easilj modified from time to 
time, .md ii serms to me that Regulations are the elastic form required. We need a Code 
Napoleon for our Building Law, and if all legal precedent for this country is against it, then 
let such matters of general policy as the width of streets, lines of frontage and rights of 
adjoining owners, space about the rear of buildings-, be enacted, but as regards the details 
of construction let them be given in Regulations that can be modified from time to time. The 
present Arts art- not only very disorderly and involved in expression but are most unscientific. 
The Steel Frame Act and the Reinforced Concrete Regulations have specified stresses, methods 
of calculation and workmanship, and it seems to me that the same oughl to be done for the 
other materials and constructional methods in vogue (such as timberwork, stonework, brickwork), 
and some which may yet be in vogue (such as reinforced brickwork, reinforced stonework, rein- 
forced Steel, reinforced glass, reinforced papier niacin', nickel-steelwork, aluminium-alloy 
work, concrete slabs and blocks for hollow and solid walls, and mi on). The regulation of 
the thickness of walls by the height of the storey is out of date in this scientific age; the 
thickness of walls should be determined by the work required thereof as to stability, resistance 
to fire, and hygienic qualities such as damp-prcofness. 

The health of the occupants of buildings is not thoroughly studied at present, for the 
proper number of changes of air per hour are not regulated, while unnecessary restrictions 
are placed upon designers who wish to give the maximum amount of light. Among other 
reforms, f should like to see greater facilities given for enabling economy to be effected in 
the construction of foundations of buildings. The maximum load that the ground will safely 
sustain should be put upon it, and footings could often be eliminated. It is important to 
know the character of the subsoil in. the preliminary stages of the design of a building, and 
there is probably a mass of information on the subject in the possession of the London County 
Council's various departments and of the district surveyors of London which ought to be 
codified and made easy of reference by the public, who might well be asked to pay for the 
work of codification, for it would save the expenditure of many thousands of pounds a year 
on building operations. 

MR HILLS' REPLY. 

Mr. Hills, in reply, said that what they really wanted was an Act embracing all the law 
in regard to buildings, and they might have some schedules or regulations added to it. A man 
wdio had to draw up a Building Act must be accustomed to that sort of work. Surveyors 
would make as much " hash " of it. if they tried to do it without a lawyer, as if a lawyer 
tried to do it without a surveyor. The suggestion that the new Building Act should apply 
universally did not find approval in his eyes. He did not think that the rules which applied 
to the suburbs could well be brought into the City. It was quite reasonable that an ancient 
city like the City of London should be exempt from all the rules which were applicable to more 
modern parts. Space was very valuable in the City, and it was not necessary to have the 
same amount of open space for an office as for a dweilingdiouse. The construction of public 
buildings was left to the district surveyors. In all other points public buildings must comply 
with the requirements common to all buildings. He agreed that there ought to be a stringent 
supervision of reinforced concrete work, and, in one case, that had resulted in the detection 
of the omission of the steel. If they left out 14 1 st lis of the whole strength of the thing, they 
would see that supervision was necessary. 

It had been suggested on the one side that district surveyors should have a great deal 
more discretion, and on the other hand that that would be a dangerous thing. Being a district 
surveyor, he might not be unbiassed, and therefore he proposed to leave it where it was. with 
a considerable divergence of opinion. In conclusion, he pointed cut that no new Act could 
bly be passed during the continuance of this terrible war, but they could certainly prepare 
for it. 



D 2 303 



NEW WORKS IN CONCRETE. 



ICONCRFXFJ 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information ivill be presented of new ivorks in course of 
construction or complied, and the examples selected •will be from all parts of the "world. 
It is not the intention to describe these ivorks in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea tvhich served as a basis 
for the design. — ED. 



ORNAMENTAL REINFORCED CONCRETE BRIDGE, 
CLACTON-ON-SEA. 

The development of Clacton-on-h'ea affords an admirable illustration of what a 
zealous and energetic local authority can do towards the making of a popular health 
and holiday resort, and during the past two years the Council has everywhere impressed 
itself to the great advantage of the town, whether regarded from the point of view of 
the resident or from that of the holiday-maker. 

A magnificent band and entertainment pavilion has been constructed on the sea 
front at a cost of /, 14,000, which work was designed and carried out by administration 
bv the Surveyor to ihe Council, Mr. D. J. Bowe. Adjoining the site of this pavilion 
was a roadway run- 
ning down from the 
centre of the town to 

the pier, and on each f 2o|ft. 

side of this roadway 
was a row of un- 
sightly small shops 
which used to ob- 
t r u d e themselves. 
These shops were 
purchased b y t h e 
Council from the 
Pier Company at a 
cost of ,6*5,000, the 
site w a s entirely 
cleared, and on their 
former position artis- 
tic rock gardens have 
been constructed and 
laid out in a ver) 
pleasing manner. 

To eonnet I the 

East and Wesl Cliffs 
and so make a con- 
tinuous promenad • "I 
over two miles along 

I he top terrace of the 

sea front, as well as 

to give quicker access 

to the pavilion, the 

bridge, here illus- Fig. 1. Half Section through Centre of Bridge. 

Crated, w as con- Ornamental Reinforced Concrete Bridge, Clacton-on-Sea. 








30+ 



E 



F tr>NxruiK-rioNAi; 

KNf.IMKl PINt. — 



ORNAMENTAL CONCRETE BRIDGE 



structed last year. It is of reinforced concrete on the " Pikett) " system, and is in 
complete harm on) with the Band Colonnade, being in the Renaissance -i\l<- and purel) 
Italian in feeling, h is probabl) one of the besl examples oi architectural treatmenl 
being incorporated with reinforced concrete work. The voussoirs are surmounted by 
■' dentil course and balustrading, with a central pediment on each side, carrying on the 
outside ol each the town's coal of arms casl in bron 




The clear span between the abutments is bo ft. (the roadway beneath being 
45 ft. wide), the width between the parapets being 20 ft., whilst the headway above 
pier gap is 15 ft. This latter height allows the lifeboat being taken on and" off the 
pier. Inasmuch as the bridge is for pedestrians only and cannot, from its position, be 
used for any vehicular traffic, it was designed to carry a super load of iA cwt per sq. ft. 
I he maximum stress on foundation is 35 lb. to the sq. in., the bearing capacity of the 
foundation level being estimated at 3 tons per sq. ft. 

The foundation slabs are 14 ft. by 22 ft. by 7 in. in thickness, and the design of the 

305 



NEW WORKS IN CONCRETE. 



ICDNCRETEJ 








u 



• o 



■ 



306 



' y , ITONSTDl ICTION A 1 1 
A t.NOlNhl K'INd — , 



ORNAMENTAL CONCRETE BRIDGE 
























O U 



o 


03 


V 


a 


„ 


H 




UcJ 


o 






U 




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o 


U 






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ac 


2i 



bridge is on the < antile\ <t sj stem. 
I he outside an li ribs are 20^ l»\ 
9 in., and the centre one .•<>'. b\ 
\2 in., whilst the ribs are con- 
nected transverselj bj beams \ ai j - 
i iii4 from 5 ft. i\ in, to 5 ft. 9 in. 
apart, and from <>' in. by 10 in. to 
(>j in. by 12 in. in size. The <l<< ic- 
ing slab is v' in. in thi< kness and 
the underneath of the bridge is 
beautifull) panelled. I he wing 
walls are 7 in. in thickness, and the 
centering of the arch was nol struck 
until the filling above the foundation 
slabs was completed up to a height 
of 9 ft. 

The floor of the bridge is of La 
Brea Asphalte, 1 in. in thickness, and 
the concrete was to the following 

proportions, viz. : cement, 510 lb.; 
sand, 1075 CU. ft. ; stone, 21*50 CU. ft. 

Three months after the comple- 
tion of the work the bridge was 
tested by an evenly distributed load 
of no tons being placed thereon and 
remaining there for some two hours 
before being gradually removed. 

The specification stipulated that 
the deflection under the test should 
not exceed 1 600th of the span, viz. : 
1 '3 in., and it was practically un- 
measurable. 

The design and architectural 
treatment of the whole of the scheme 
was the work of Mr. Daniel J. 
Bowe, the Council's Surveyor, 
whilst the reinforced concrete details 
were supplied by Messrs. Paul 
Pikettv and Co. The work in con- 
nection with the bridge was carried 
out by Messrs. W. Archer and Son, 
of Gravesend, under Mr. Bowe's 
supervision .and control, with Mr. 
\Y. T. Morrison as clerk of the 
works. The cost of the bridge, with 
coat of arms panels, wrought iron 
electric light standards, and a few 
other miscellaneous items, was just 
over /Ti,ooo. 



•ft 






3°; 



NEW BOOKS. 



[CONCRETE] 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books 'which have appeared during the last feiv months. 



Reinforced Concrete in Practice. By A. 
Alban H. Scott. 

London : Scott, Greenwood and Son, 8 Broadway, 
Ludgate, E.C. 178pp.+viii. Price +/- net. 

Contents. — General Notes — Materials — 



of Materials — Centering — 
Preparation of Steelwork — Concrete 



Testing 



—Striking 



of Centering — Cutting 



Away and Making Good, Surface 
Treatment and Finish — Work Re- 
quiring Special Method — Fixing of 
Machinery, Plant, etc.— Testing of 
Finished Structure — Contraction, Ex- 
pansion. 
The author states a great truth in his 
preface when he says that there is no 
building material so lasting and requiring 
less maintenance than reinforced concrete, 
but it should only be employed when the 
work is under constant, careful, and ex- 
perienced supervision, and when every 
material in the work is tested; and this 
volume is very welcome because it puts 
forward information useful to those en- 
gaged in reinforced concrete work, which 
information is based on the right principles 
and consequently it deserves to be popular. 
The notes are presented in such a manner 
that the interests of all parties are con- 
sidered, and while those points conducive 
to good practice are impressed upon the 
reader, many useful hints dealing with the 
economical execution of the work are given 
for the benefit of the contractor. 



In the general notes the author states 
that great improvements have been found 
in work executed where the foreman 
explains to the ganger and he in turn ex- 
plains to his men in their own particular 
language the different functions the mate- 
rials fulfil. The preparation of the draw- 
ings and the lay-out of the work on the 
site are also discussed. After dealing with 
the materials some very good practical 
notes on the centering are given, and these 
are illustrated with numerous photographs 
of actual work, as is also the following 
chapter on the preparation of the steel- 
work. 

The question of concreting is fully con- 
sidered from the point of view of obtaining 
good work, and some useful notes are 
given in connection with the temporary 
suspension of concrete, which is an im- 
portant problem. The work described in 
the chapter dealing with that requiring 
special method includes chimneys and 
other constructions subjected to high tem- 
peratures, tanks, and piles. 

The book is well written and well illus- 
trated throughout, and it is practical in 
character, rendering it suitable for a great 
number of readers of all classes, and it can 
be recommended as a handy volume which 
will prove very useful to those engaged in 
the design, supervision, and execution of 
reinforced concrete work. 



308 



\ 2, coNyreucnoNAE 



CORRliSI'ONDKSi 



CORRESPONDENCE. 

Under this heading •»;>«• invite correspondence* 



To the Editor ol Con< ri m \m> Constru< lIOnal Engineering. 

Sir, The solution of the arch problem in your lasl issue, p. 230, is interesting, bul 
is not applicable to the case of the brick arch in question. This was a half-brick arch, 
built as a cover only, which fell directly the centering was removed. My solution of 
the case is given in the diagram herewith, where the curve of thrusl is assumed to pass 
through a point one-twentieth of th<' span above the neutral axis al the crown, and 




SCALE OF FEET 
ins 12 6 O 1 2 

i I' . il..l I -4- 



5FT 



lOO SO 

I . I I I I I 



SCALE OF LBS 
lOO 



500 



through the neutral axis at one-twentieth of the span above the springing. This is 
an empirical solution only, and Mr. Andrews was asked if he could prove it by mathe- 
matical analysis. 

The horizontal thrust is found graphically to be about 118 lb., and the bending 

moment 118 x — (10 x 12 + 4'5) = 734*55 lb.-in. The maximum stress at the crown will 

20 

then be— ± — = 118 +- /34 D3 9 = 2'185 + 18*137 = 20*3 lbs. per sq. in. compression 
A Z 12X4"5"~ £X12X4"5 2 ~~ 

and I5'95 lb. per sq. in. tension, so that, had the arch been built in cement mortar and 
been allowed to set before the centering was removed, it would probably have just 
succeeded in standing. 

Henry Adams. 



309 



INDUSTRIAL NOTES. 



[CONCEBTE1 



INDUSTRIAL NOTES. 

These pages have been reserved for the presentation of articles and notes' on proprietary 
materials or systems of construction put forivard by firms interested in their application. With 
the advent of methods of construction requiring considerable skill in design and supervision, 
many firms nowadays command the services of specialists whose views merit most careful 
attention. In these columns such views will often be presented in favour of different 
specialities. They must be read as ex parte statements -with -which this journal is in no vjay 
associated, either for or against — but ive ivould commend them to our readers as arguments by 
parties V)ho are as a rule thoroughly conversant with the particular industry 'with "which they 
are associated. — ED. 



A NEW METHOD OF REINFORCED CONCRETE SHEET PILING. 
Reinforced Concrete Wharf at Great Yarmouth. 

A new method of reinforced concrete sheet piling has recently been employed for the 
construction of a new wharf front at Great Yarmouth on the River Yare. The work 
was carried out for Messrs. H. Xewhouse and Co.,. A. B.C. Wharf, under the super- 
vision of Mr. F. G. Turner, Engineer to the Harbour Commissioners. 

The new method of piling employed, which goes under the name of " The Coignet- 




-AJl£Mr/0// 



2 



V 



I 



&ac& Water 



Ravier System," consists in driving al intervals of about 6 or 7 ft. a certain number of 
piles fitted with lateral wings or sheeting, the intervening space between the sheeting 
and the main piles being filled Up by other similar wing piles driven at the back of the 
front row, the object being to form a continual quay front by means ol these wing 



7, IO 



I 



OONMUUCTIUNAi: 
EJMCJNhl PINO -^ 



INDUSTRIAL NOTES, 



pile-, which are held in position l>\ being driven sufficient!) into the ground l>\ means 
of a steam monkey, and held back h\ means "I 1 1 in l« u 1 1 <1 concrete land ties and anchoi 
plates. 





M Ml Jh** *** 




View of Quay with Timber Fenders. 




King Piles maturing until ready for driving. 

The principal advantages claimed for this method are that a much smaller number 
of piles requires to be driven than in the case of continuous king piles and sheet piles, 

3" 



INDUSTRIAL XOTES. 



[QDNCRETEl 



and also a certain amount of economy 
in the actual steel and concrete require d. 

The plans were prepared by Messrs. 
Edmond Coignet, Ltd., of 20, Victoria 
Street, Westminster, who are the 
patentees of this new method, which 
has already been employed recently for 
the construction of a wharf front for 
the Harwich Gas Works. This new 
method of sheet piling has also been 
extensively used on the Continent. 

The photographs reproduced here- 
with show the general appearance of 
the finished structure, with timber 
fenders for the protection of the 
reinforced concrete work. The total 
length of the quay front will ultimately 
be about 2^6 ft. The total length 
of the main piles from the top to the 
end of the shoe is 32 ft., and the length 
of the wings measures 25 ft. with a 
width of 2 ft. q in. The intermediate 
wing piles are also 32 ft. long with a 

panel of 25 ft. in length by 4 ft. 6 in. 

in width. 

The work was carried out bv Mr. 
A. W. Chastncy (Wick and Sons, Ltd.), of Norwich 



7dfctAezi ? f6 *£_ Mkrf £46" 3 




<£fccr/0//M rtm 




ATafe 



/"vf/z/Zf^j 



fi&tt 3zcr/&/y 




312 



j, CONMUlKTIONAl. 

"v tjsj( ,1 n kkwino — 



CONCRETE POSTS FOR LETTER BOXES, 



POPULAR USES. 

Under tivs heading it is proposed from time to time to present particulars of the more 
popular uses concrete and reinforced concrete can i >■ put, .is, for Instance, In the 

construction of houses, cottages, on ///<• farm and on tin- road* Previous articles vrill /<* 
found m our issues of Det.emher, 1912 / January, M.mh, July, Ottoier and November, 

1°14 ; And January and February of this yejr. ED. 



CONCRETE POSTS FOR LETTER BOXES IN USA. 

1 in accompanying illustrations show a novel use of concrete. Ii is a post supporting 
a letter box on a rural free deliver) route near Dallas, Texas. The concrete features 
consist of the post or support for the box. Wooden posts as used there are always 
su6ject to rapid decay at the ground level, where alternate wetting and drying takes 

place, and to avoid the necessity of renewals and repairs the concrete post was made. 

Tile form for casting a post ol this kind is shown below. The post should be 
about 7 ft. long. Planted at a depth of 3 ft. this would leave the box at convenient 
height for the delivery or extraction of mail. Tin form, as shown on the drawing, is 
simply a ihree-sided box providing for a post 
u in. square. The form is placed on the 
ground in horizontal position, with open side 
up, and filled with well-tamped concrete to 
the depth of about i in. Then |-in. rein- 
forcing rods are placed at either side, leaving 
about 1 in. space between each rod and the 
side of the form. The box is then filled to 
within 1 in. from the top and two more 
reinforcing rods are placed on the concrete. 
The form is then filled to the top and the 
concrete struck off. The rods may go straight 
from the bottom to the top of the post, as it 
will not be necessary to curve them outward 
at the bracket. 

The form or mould may be made with 
one or more braces nailed across the upper or 
open side to prevent the sides from spreadinv' 
when the concrete is tamped. The bracket 
effect at the top is obtained by inserting extra 
pieces of wood at the corners, as shown. If 
preferable a post in the shape of a letter T 
may be made, eliminating the bracket 
feature. A perfectly plain post without 
projecting top would also answer the 
purpose. 

To provide for fastening the letter box to 
the post, bore two or perhaps four holes 
through the board at the top of the form. 
Insert in these holes the bolts with the heat's 
down, or inside the form. The bolts will be 
embedded in the concrete when it is placed, 
f.nd when the form is removed the threaded 
ends of the bolts will project slightly above 
the top of the post. Holes cut in correspond- 
ing position in the bottom of the letter box 
will permit the bolts to pass through and the box will be secure when nuts are placed 
on the bolts. 

Mix the concrete in the proportion of i part Pottland cement, 2 parts sharp, clean 
sand and 4 parts crushed stone, ranging from \ in. to 1 in. in size. Allow the concrete 
to remain in the forms for at least 24 hours. When the post is removed protect it from 




Coxcr.ETE Mail Box Post nkar Dallas. Tkx. 



1*3 



POPULAR USES. 



(COMPETE 



freezing or, if made in summer, from hot winds and sun. Wet it thoroughly for a 
week or ten days after removing it from the forms. 

Concrete posts do not warp, decay or burn. When used for fencing they keep in 
better alignment than wooden posts. Concrete is now largely used in America for fence 



T 







/osition of 
m Corncr^r 



Form for Casting a Concrete Post similar to that shown above. 

posts, clothes poles, hitching posts and gate posts. Concrete fence posts have been 
made at an average cost of less than 25 cents each, notwithstanding the fact that all 
material was purchased, and even in well-timbered districts they are being substituted 
for wooden posts on account of their low first cost and everlasting qualities. 



3'4 



j. lONM IMRTIUNAl 
'V KNCilNM W1NO —, 



MEMORANDA. 




Memoranda and Neivs Items are presented under this heading, with occasional editorial 
comment. Authentic neivs ivill be welcome. — ED. 



The National Road Conference and Exhibition (1915). This Conference and 
Exhibition is to be hold in London at the Royal Horticultural Hall, Vincent Square, 
Westminster, from June 25th to July 1st. 

It will be opened on June 25th by the Right Hon. Herbert Samuel, M.P., late Presi- 
dent of the Local Government Board. The Conference is organised by the County 
Councils Association, and will take place concurrently with the Annual Meeting of the 
Institution of Municipal and County Engineers. 

The preliminary arrangements are as follows :- — 

June 25th and 26th.— Annual Meeting of the Institution of Municipal and 

County Engineers, when the following subjects will be discussed : — 

1. The improvement and maintenance of highways in connection with modern 

traffic conditions. 

2. The use of reinforced concrete in buildings, road construction, etc. 



Town Planning. 



horse power from an economical point of 



4. Haulage by mechanical means 

view. 

5. Restriction and control of heavy traffic both as regards weight and speed. 

6. The maintenance and strengthening of iron and steel bridges. 

June 28th. — Conference on " The adequacy of bituminous roads, with special 
reference to the subject of corrugations," and other matters. 

June 29th. — Conference on Heavy Traffic. 

June 30th. — Morning: Meeting of Executive Council of County Councils 
Association. Afternoon: Conference on the Classification of Roads. 

Julv 1 st. — Conference on the Reconstruction of Roads in Belgium arranged 
jointly by the County Councils Association and a Special Committee which has 
been formed in connection with the Rebuilding of Belgium. 

Arrangements as to other meetings on the above days will be announced 
separatelv as soon as the full programme is definitely settled. 

Regarding the Exhibition, the latest date for the reception of exhibits is Wednes- 
day, June 23rd, 11 a.m. 

The Organising Secretary is Mr. G. Montagu Harris, from whom all particulars 
can be obtained on application at Caxton House, Westminster, S.W. 

Fires Due to Air Raids, etc. — As it is within the bounds of possibility that 
attempts may be made to start incendiary fires, the British Fire Prevention Committee 
make the following suggestions : — 

(a) The various Fire Brigades cannot be expected successfully to deal with 
any large number of outbreaks, and their attention would in any case be primarily 
devoted to fires affecting Government offices, workshops engaged on Government 
work, military stores, docks and hospitals and the like, rather than to private 
property or semi-public property, however valuable. It therefore behoves all 
owners and occupiers of such premises to do their best to organise for self-help. 

(b) Innumerable establishments such as factories, warehouses, stores, modern 
office blocks, flats, hotels, and large private houses, as also the semi-public 
establishments like sehools, baths, theatres, music halls and assembly rooms are 

3*5 



MEMORANDA 



iOCJNCEEXEi 



equipped with internal hydrant services and first-aid fire appliances. These should 
be promptly examined and the staffs (both male and female) frequently praetised 
in handling the gear. The smaller establishments, such as shops, offices and 
ordinary domestic buildings should have an ample supply of buckets (kept ready 
filled with water), and where funds permit, one or more small hand-pumps. Occu- 
pants should know how to use these appliances efficiently. 

(c) Every effort should be made by the public to assist the Fire Brigades in 

their onerous duties, but they should not omit on any account immediately to 

notify any outbreak that comes to their notice by telephone or otherwise — the 

method of calling assistance to be posted up in a conspicuous position. 

Concrete Buildings for Small Holdings. -Mr. T. P. Bonsor, F.R.I.B.A., who 

was awarded the prize by the Royal Agricultural Society of England for the design of 

house and buildings for a small holding, in a paper on the construction of such buildings 

says that, save from its aesthetic standpoint, concrete possesses even more advantages 

than brickwork, and, where gravel or other suitable aggregate is very cheaply procured, 

and the amount of work to be executed is sufficient to warrant the construction of 

the special framing required or the purchase of suitable appliances for making it in 

blocks, may be used with advantage. 

Tests of Six Types of Reinforced Concrete Fence Posts. — Six types of 
reinforced concrete fence posts have been tested under the direction of the Committee 
on Signs, Fences and Crossings of the American Railway Engineering Association. 
All posts were made of 1:2:4 concrete, using broken stone or gravel aggregate not 
more than i in. in size, and were about one year old when tested. Two round, one 
square, one half-round, one T-shaped, one triangular section were used, all 7 ft. long, 
all of tapering outline except the last. The reinforcement consisted of various sizes of 
steel wire or rods, and the lateral dimensions varied from 5 to 6h in. at the base to 3 or 
4^ in. at the top, reinforced with six No. 8 wires. The other smaller circular post 
reinforced with five wires also gave very good results. The tests indicated that this 
form of post, with several reinforcing wires, or the T-form with three 3-in. rods, was 
the strongest and most reliable. 

The Effectual Sealing of Water Dams by Cementation. — In a paper recently 
read before a meeting of the National Association of Colliery Managers, at Leeds, 
Mr. Frank N. Waterhouse read an interesting paper on the above subject. The paper 
was reproduced in the Iron and Coal Trades' Review, from which journal we pub- 
lish the following extract : — 

In introducing his subject. Mr. Waterhouse said that at one of the collieries of 
which he had charge there were two seams being worked — the Old Hards or Park- 
gate, and the New Hards or Silkstone, the former lying at a depth of 116 yards from 
the surface-, and the latter at 165 yards. On the north side of the Pit there was a 
72-yard dip fault, which placed the Old Hards 22 yards below the New Hards. 
Another fault, which lay about 300 yards parallel to the first one, rose 23 yards. Two 
drifts were driven down the 72-yard fault to the Old Hards seam, the back drift at an 
inclination of 1 in 2, and the main drift at 1 in 6. A small area of coal was then 
worked out between the two faults, but as it proved very faulty it was decided to 
prove the rise faults. Accordingly a drift was driven at an inclination of 1 in 2, and 
then the main drift was driven in the rise at 1 in (>. The coal was opened out by 
headings, and water began to be very troublesome in roof, coal and floor. The seam 
was 20 in. in thickness, and had a fireclay seat. 

A coal-CUtting machine was installed and every effort made to get a good area of 
coal worked out. It was anticipated that the water would ultimately drain off. A 
pump capable of dealing with it was installed, but there was great difficulty in keeping 
up th<- roof in the face and the gates, and the quantity of water had steadily increased 
until it amounted to 60,000 gallons per daw It was therefore decided to close the 

district and dam back the water to avoid further pumping. 

The firsl dam was built in the back dam drift, the site being prepared in the 
usual way by shearing the sides back and cutting in the floor and roof to secure solid 
ground. The main drift dam was then built ; both were built with concrete and 
casing walls, the concrete being heavily reinforced with old wire ropes. When the 
valves were closed and the water allowed to fill up, the pressure gauge reading 
increased until it reached go lb. per sq. in. At this stage the dams held tight, but the 

316 



>. cioNMUurnoNAi; 

MM.IMI RING — '. 



MEMORANDA 



defective strata above referred i * > allowed the watei to leak, the leakage being about 
one-hall i»t the original feedei ; quite two-thirds came from the back <lrih dam. All 
the time this leakage was allowed to continue the pressure "I 50 lb. per sq in. re- 
mained constant. It was then thoughl advisable to pul another dam in the back drift. 
Pitchpine blocks, 5 ft. long l>\ 10 in. square at the back, planed and tapered, wen 
prepared on the surface and numbered. A level concrete bed was placed 9 ft. in fronl 
of the oilnr dam, <>n which tarred flannel was laid to make the bottom joint in the 
ring, the joints between the blocks and roof and sides being made b) ramming 
oakum with special tools. A 16-in. square cast-iron pipe was put in for a manhole 
and a pin. square pipe for 1 li«- water to escape; these were made square so as to be 
able to til the timber and make a ti^ht joint. 

An additional dam was built in the main drift 10 yards in front ot the other, and 
ii was hoped that the strata surrounding the new dams would prove water-tight. 
I In water, however, dripped out in places two or three yards in front of the dam in 
the back drift, and the amount of leakage there was only slightly reduced. The dam 
in the main drift was good, except that at a short distance away there was a slight 
trickle of water in the floor. The advisability of adopting the cementation process <>l 
solidifying broken strata was then considered. A horizontal pump having a cylinder 
10 in. diameter, [2-in. stroke, and a 2-in. ram, was used to inject the cement. Power 
to drive the pump was obtained by use of compressed air at a pressure oi 75 lb. per 
sq. in. The suction pipe was connected to a tub in which the cement was mixed, the 
tub being fitted with a revolving arrangement which was worked by hand for stirring 
the water and cement. 

Before pumping was commenced the 9 ft. of space between the two dams in the 
back drift was filled with broken bricks and stone. Three 2-in. pipes were laid through 
the manhole, rising one above the other. A thin iron plate was bolted on the manhole 
out-bye end with the pipes projecting through the plate, the two upper pipes were plugged, 
and the bottom one connected to the delivery pipe of the pump. Cement and water were 
mixed in the tub until there was a mixture like thick mud. The pump was then 
started at 30 strokes per minute. After 40 hours' pumping the space was filled with 
cement, and the pressure gauge reading on the pump began to rise very quickly; the 
solution was then made thinner and pumping was continued until the pressure was 
1,700 lb. per scp in., when the pump stopped, not being able to force any more 
cement into the strata and the space between the dams. At the close of this work it 
was found that the whole of the operations had been successful, the water being 
completely stopped. 

A wall was then built iS in. thick in front of the dam, leaving a space of 9 ft., 
which was filled with broken stone, and cement was then injected in a similar manner 
as in the back drift. 

During the progress of this operation the pressure produced by the injection oi 
the cement affected the strata for some 6 yards on the out-bye side of the dam, thus 
showing the line fissure of the strata, and, on the other hand, the pentrating power 
of the fine liquid cement under heavy pressure. 

At one period it was thought that it would be necessary to bore Hank-holes in the 
strata, in order to give the cement direct" access to the line fissures. However, it was 
found in both cases that the injection behind the dams had proved successful. 

In conclusion, Mr. Waterhouse suggested that, in the process of cementation, 
colliery managers had an additional ally with which to overcome difficulties of the 
nature he had described. 

Nairobi Stock Exchange Bui/dings. Mr. J. K. Watson, the general contractor, 
has completed the first portion of the Nairobi Stock Exchange, which occupies a 
position in the principal thoroughfare. The facades are faced with stone and backed 
with concrete, and all the interior walls are constructed of concrete. The Kahn rein- 
forcement for the floors and flats, etc., was supplied by the Trussed Concrete Steel 
Co., Ltd., Westminster. 

Expenditure on Public Works. —At the commencement of the war most of the 
local authorities of Great Britain looked round to see what works of public improve- 
ment might be taken in hand so as to cope with the unemployment that was feared, 
and it seemed as if many projects, in which concrete would form a large part, would 
be carried out. Scarcity of labour for the carrying out of Government work has caused 

K 3 17 




"L— 



CONCEEFEX 



CONSTRUCTIONAL^ 
ENGINEERING — 





Illustration shows a Travelling and Traversing Steam Pile 

Driving Plant, built by us for the Crown Agents for the Colonies, 

for constructing a Reinforced Concrete Jetty at Lagos. 

The Hammer is of our single-acting semi-automatic type, 2 J tons 

in weight. The under-frame of the plant is of steel throughout, 

has an overhang of 12' 6", and travels on three sets of wheels. 

Telescopic leaders with ladder were supplied with the Pile 

Driving Frame. 

This plant is of our standard type, so that the under 

carriage may be dispensed with and the plant used for ordinary 

pile driving work on completion of the Jetty at Lagos. 

Weights of Piling in stock on sale : 

» SIMPLEX " 22 to 27 lbs. per sq. ft. 

"UNIVERSAL" - from 43 lbs. 




rj r CON.N i unci ION A l} 
[ fvl-.NfilNKV.WlM'i ^J 



MEMORANDA 



the Treasury to restrict capital expenditure on these projects, with the result that man) 
of them li;i\ e been postponed. 

LITERARY NOTE. 

Messrs. Chapman and Hall have ready for publication a text-book on the 
14 Strength of Materials," by Mr. Ewart S. Andrews, B.Sc, whose books upon ihc 
»« Theon of Structures," published l>\ the same firm, have had a wide circulation. 
The present book is based upon the same general lines, the two subjects having much 
in common, and comprises twenty chapters dealing with Stress, Strain and Elastieit) ; 
The Behaviour of Various Metals under Test; Repetition of Stresses, Working 
Stress^; Riveted Joints and their Pipes; Bending Moments and Shearing Forces on 
Beams; Geometrical Properties of Sections; Stresses in Beams; Deflections of Beams; 
Columns, Stanchions and Struts; Torsion and Twisting of Shafts; Springs; The 
Testing of Materials; Fixed and Continuous Beams; Distribution of Shearing Stresses 
in Beams; Flat Plates and Slabs; Thick Pipes; Curved Beams; Rotating Drums, 
Disks and Shafts. 

PROPOSED NEW WORKS. 

Patea iNe\s Zealand).- -In connection with the loan recently secured by the Patea 
Harbour Hoard, New Zealand, the Marine Department has approved plans for the 
improvement of the port, and tenders have been invited for the extension of the existing 
breakwater in concrete on the " pierre perdue " system. 

West Hartlepool. Messrs. W. Gray and Co., Ltd., contemplate the construction 
of two graving docks, a fitting-out basin, and a number of building berths on a new- 
site acquired by them near Seaton Snook, at the mouth of the River Tics. Mr. I. ('. 
Barling, of Middlesbrough, is the engineer. 

Guernsey. — The St. Peter Port Harbour Committee, Guernsey, have invited 
tenders for the erection of a concrete tower upon the Roustel Rock, in the Little Russ 
Passage on the eastern side of the island, but no contract will be entered into until the 
registration of His Majesty's Order in Council authorising the execution of the work. 

Alexandria. — The Egyptian Estimates for 1915 make provision for the reinforce- 
ment of the breakwater at Mole E and Quay R in Alexandria Harbour. 

Clacton. — A Local Government Board enquiry has been held into the application of 
the Urban District Council for sanction to borrow ^0,150 for works of sea defence. 
The proposal is to replace a further portion of the old timber wall with massed concrete. 
It will be 20 ft. in depth at the face and 21 ft. at the back; 9 ft. in width at the 
bottom and 3 ft. 6 in. at the top below the coping. 

Port Talbot. — Considerable developments are anticipated at Port Talbot, and the 
Port Talbot Railway and Dock Co. are making preparations. Messrs. Baldwins, Ltd., 
have leased about 40 acres of land by the side of the Margam Dock for new works, 
and will construct a reinforced concrete wharf alongside the new works. 

Caerphilly. — Tenders have been invited by the Urban District Council for the 
construction of a concrete retaining wall adjoining the Rhymney River at Pwllvpart. 

Reading. — The Town Council have instructed the Town Clerk to enquire of the 
Local Government Board if they will approve of the borrowing of the sum necessary 
for the construction of the De Bohun Road bridge in reinforced concrete. 

East Africa Protectorate. — A Bill has been passed by the local Legislative Council 
providing for a loan of ,£1,868,000 from the Imperial Treasury to be expended on works 
in the Protectorate as follows: — Kilindini harbour works, ,£640,000; railway improve- 
ments, ^.a)57,ooo ; roads and bridges, ,£100,000. 

Brazil. — The city of Pernambuco, Brazil, has under construction an electric power 
house of reinforced concrete. 

Withernsea. — During the month the Urban District Council have invited tenders 
for the erection of a reinforced concrete wall at the South Cliff of a length of about 
450 yards. 

Sunderland. — A House of Lords Committee has passed the preamble of the Bill 
of the Corporation for the reconstruction of YYearmouth Bridge at a cost of nearly 
^£170,000. 

Carlisle. — The Rural District Council have invited tenders for the construction in 
concrete of a water tank at Wetheral Shields. 

319 



MEMORANDA. 



IIONUJEIKJ 



Metropolitan Water Board. The Hoard have decided to improve the coal storage 

bunkers at Hampton, and will carry the bunkers on a reinforced concrete pile 
foundation. 

Eston. The Tees Conservancy Commissioners have approved plans submitted by 

the North-Eastern Railway Co. for the construction of a line of deep-water quays 
about a mile in length at Eston. It is not expected, however, that the scheme will 
be proceeded with until the war is ended. 

Concrete Mouses at Linthwaite.— A report has been submitted to the Linthwaite 
Urban District Council by Mr. J. Ainley, the architect, on the scheme for the erection 
of concrete houses for the working classes. The scheme was for 89 houses at a cost 
of ,£.'26,000. Sixteen houses have been erected at a cost of ^3,613, exclusive of land. 
Rents were yielding ^196 per year; repayments of principal and interest amounted 
lo A'i<)o, and the cost of repairs was ;£i6. 

CONTRACTS ACCEPTED. 

The Unit Reinforcement Construction Co., Ltd., have just received the follow- 
ing two contracts : — 

950,000 gallons filtered water reservoirs, wash-out tanks, and lime pits at Black- 
moorfoot, for the Huddersfield Corporation. J. W. Armitage, Esq., Water Works 

engineer. 

Extensions to works for Messrs. Middlemosts Bros., Huddersfield. Messrs. Stocks 

and Sykes, architects. 

CONTRACTS OPEN. 

Minehead. — Tenders are invited by the Somerset County Council for the provision 
of a concrete apron of a length of about 750 ft. ; the construction of a length of 120 ft. 
of new sea wall, and the construction of a reinforced concrete casing to Pill Bridge 
outfall. Specifications, etc., may be obtained of Mr. E. Stead, the county surveyor, 
Wells, Somerset, on a deposit of- ^3 3s. Tenders returnable on June 5th. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum ^-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 



The VICTORIA 

is built to last 

WRITE FOR CATALOGUE No. 29. 



THE 

T. L. SMITH Co. 

13, Victoria Street, S.W. 



320 



Please mention this Journal when writing* 







- - T ~ -. ' :.;.-.. 




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5 -c 



wRSFx^^-'^^y^ "• 'V- ^ 



CONCRETE 



Volume X., No. 7. London, July, \y>\5. 

EDITORIAL NOTES. 



CONTRACTORS AND REINFORCED CONCRETE. 

The existing state of affairs as relating to the general building contractor and 
the tendering and execution of reinforced concrete leaves much to be desired, 
from the contractor's and the designer's point of view, and it is in the hope 

of arousing some interest in the conditions that we put forward our remarks. 
The consulting engineer and the speeialist are in the hands of the contractor 

when the estimating and execution come to be considered, and it therefore 
follows that with the most careful calculations and quantities a great variation 
of price will result with different contractors, and even with the most careful 
supervision errors are liable to occur if the builder is not well versed in the 
nature and properties of the material which he is using. 

It is true that a limited number of contractors have priced and executed 
reinforced concrete to a large extent, and these are able to produce satis- 
factory results ; but the majority of builders have had little or no experience, 
and are really not competent to enter the market as competitors under 
the present conditions. Apart from special licensed contractors, and special- 
ists who execute the work themselves, the general method now adopted when 
reinforced concrete forms the whole or part of the constructional material in a 
building is lor the engineer, whether specialist or otherwise, to prepare a 
scheme with the necessary details from which the quantities are taken out, 
and the bills are then sent out to several builders for quotations. If the bills 
form part of the quantities for the whole building, then the tenders obtained 
are for the whole of the structure and finishings, and when the reinforced 
concrete is dealt with by a specialist firm apart from the building generally 
the lowest estimate is introduced as a provisional amount in the main contract. 
In the latter case it follows that, if the lowest estimate for the reinforced concrete 
is not given by the contractor who is also lowest in the building tenders, 
two separate contractors will be employed, and this is not conducive to economy 
or speedy erection, and it is preferable to adopt the former method in which 
the reinforced concrete quantities form part of the bills for the whole building. 
In order to do this satisfactorily, however, it is necessary either to invite 
tenders for the whole building from contractors who have had special experi- 
ence in reinforced concrete, or ask for prices from various firms, regardless of 
previous experience, and thus run the risk of an inexperienced firm being the 
lowest. 

In a recent case, when the bills for the reinforced concrete work, which 
formed about one-third of the whole work in the building, were included in the 
general bills, some very good tendering was obtained, but it was found that 
the total price of the reinforced concrete work varied more than 40 per cent. 

b 3 21 



CONTRACTORS AND REINFORCED CONCRETE. [CONCRETE] 

in the highest and lowest tender, and this in spite of the fact that the quantities 
were most carefully prepared, and the contractor had no speculative items to 
deal with. The architect wished to invite some of the builders who had done 
building work generally for him for many years, and the list included some who 
had little or no previous experience in reinforced concrete work. Some of 
the contractors actually expressed their doubts and uncertainty in preparing 
their prices even with such complete quantities, and this feeling- was caused 
simply because they were dealing- with a material which they did not under- 
stand. The remedy is really in the hands of the contractors themselves, as it 
behoves them to study the material and its properties, and thus they could deal 
with it in an intelligent manner. We do not. mean that every contractor should 
devote years of study to the theoretical design of the material, but he should 
study it sufficiently to understand those principles which govern the design and 
disposition of the component parts, he should be able to appreciate the relative 
values of the steel, concrete and centering. How is it possible for a builder to 
carry out successfully any scheme when he is working in a material with which 
he is not in sympathy? It will be found that it is only those who do not under- 
stand the material that have so much to say against it, and it is a positive fact, 
pio\ed by long experience, that when the subject is studied, and the theoretical 
and practical principles are thoroughly understood, then and then only do 
designers and builders become enthusiastic about the use of the material. 

If several contractors were called upon to price an ordinary bill of quan- 
tities of constructional steelwork, would there be a difference of 40 per cent, 
in the tenders? It is very unlikely, and it would also be incorrect to say that 
any one of them would be dubious about executing the work ; but the same 
remarks do not apply to reinforced concrete. The ordinary contractor would 
probably not hesitate to calculate a simple beam or column if he were asked to 
give a suggestion in a steel building, but he would be quite incapable of doing 
the same thing in the case of reinforced concrete, and that is where the fault 
lies. It is not that one wishes the builder to design or give suggestions, but 
is only an illustration of his knowledge of one form of construction and his lack 
of knowledge in the case of the other. 

This is the age of science, and reinforced concrete being essentially a 
scientific material is bound to become more universal every day, and unless 
those responsible for the execution and pricing keep abreast of the times, and 
study the scientific application of a scientific material, they will be left behind 
and their interests will suffer. 

The builders of the next generation will look upon reinforced concrete in 
a very different manner, simply because the subject will be included in their 
training ; but there is no reason why the present-day contractor should not 
make himself proficient, and the architect and specialist would then feel they 
were obtaining tend< rs from one who was conversant with the material. 

The application of reinforced concrete has been greatly hampered in the 
past by the attitude of architects and contractors who fail to appreciate the 
advantages oi the material, but whereas the former can generally make a choice 

in the matter, the latter have none, and they must either price and execute 
in a satisfactory manner or lose ;i large portion of their work in the future. 



322 



jri'oivyn.'iK-noNAi: 

A I NT.1NI 1 l.'INC.^. 



CONCRETE BRIDGE NEAR MERTHYR, 




REINFORCED 

CONCRETE 

BRIDGE 

NEAR MERTHYR. 



By CHAS. E. HOLLOWAY, B.Sc. 



This bridge is entirely of Reinforced 
Concrete, and affords an interesting 
example of the application of this 
material to braced girders of considerable 
span and abutment zoalts of large 
proportions. — ED. 



Introduction. — The bridge described in this article was built for Messrs. 
Nixon's Navigation Co., Ltd., of Merthyr Vale, under the direction of 
Mr. W. T. G. Marsh, their engineer, to convey the refuse colliery shale from 
their Merthyr Yale pit to the new site which they have acquired for their 
spoil tip. 

As seen from Figs, i and 2, the Rhymney railway line and the Glamorgan- 
shire Canal run side by side between the pit workings and the new tipping site 
on the mountain, the new bridge carrying the track for the spoil trams across 
these obstacles. At this point the railway and canal are about 80 ft. apart and 




Fig. 1. General Plan. 
Reinforced Concrete Bridge near Merthyr. 

run on embankments of considerable height, and the general outline of the 
bridge is governed by the following requirements : — 

(a) Height from rail level of Rhymney railway to under-side of girders at 
lowest point is 20 ft. 

b 2 323 



CHAS. E. HOLLOW AY. 



[CONCRETE] 



(b) Gradient of bridge deck i in 18 towards mountain. 

(c) Distance from centre of railway to face of railway abutment is 30 ft. 

(d) Face of canal abutment is at canal fence. 

\e) The abutment walls retain the embankments of colliery spoil, which 

form the approaches to the bridge. 
The distance between the abutments in the clear is 187 ft. 8 in., and the 




SPOIL BMMK APPROACH 



Fig. 2. General Elevation. 
Reinforced Concrete Bridge near Merthyr. 




Fig. 3. View of Completed Bridge. 
Reinforced Concrete Bridge near Merthyr. 

heights of the abutments from foundation to formation level are 44 ft. and 
40 ft. respectively for the canal and railway sides. 

A scheme was originally prepared for a bridge with masonry abutments 
similar in outline to Fig. 4, with three steel plate girder spans supported by 
tw ) masonry piers. The amount of masonry involved was very great, as the 
abetment walls were to have been 10 ft. thick. This was undesirable, firstly 
because it would have been very costly to get so much material to a site so 

3H 



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^KMC.lNV-l-.k'lNt. —J 



CONCRETE BRIDGE NEAR MERTHYR 



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CHAS. E. HOLLOW AW 



[CONCRETE ] 



difficult ol access, and secondly because the ground in this locality is very 
unstable owing- to the workings underground. 

The attention of the owners was eventually directed to reinforced concrete 
as the suitable method of construction owing to its lightness and elasticity, and 
the scheme illustrated in Fig. 4 was selected, being the tender of Messrs. S. 
Robertson, Ltd., of Bristol, on designs and specifications prepared by the author. 

This scheme, which embodied three solid-webbed reinforced concrete girder 



DEVELOPED FRONT ELEVATION 




Fig. 6. Elevation and Flan of Canal Abutments. 
Reinforced Concrete Bridge near Merthyr, 

spans, was finally altered to the two-span braced Warren girder bridge shown 

in Fig. 2, owing to a dispute about the pier resting on the canal bank. Fig. 3 
gives a general \iew of the finished structure. 

Abutment Walls. — The abutment walls are (.1" very light design and show 
a large saving over other methods of construction. The erection is somewhal 
more complex, but presents no difficulty if properly organised and carried out by 
men experienced in this class of work. 
326 



[»,CON.NTkUIC T1UNAL 
^t Vl.N(.lM 1 I-'INO — , 



CONCRETE BRIDGE NEAR MHRTHYR. 



Fig. 6 gives an elevation and plan i I the canal abutmenl walls, and Fig. 7 
shows a section near the centre line ol the bridge. A view <»l the back oi this 
wall is also given in the title illustration. Undei the girders the wall is \\ ft. 
high and 1 .] ft. 6 in. wide, and is vertical. The wing's extend f< 1 30 ft. on each 
side, and arc 27 ft. high at their extremities. They are battered back al 1 in 1 -\ 
and slope back from the vertical face at an angle <>l 30° in plan. 

The walls arc finished with moulded caps and coping, as illustrated in 
Figs. 2 and 7, the general 
effect being very satisfac- 
tory. The wall slab is 6 in. 
t h i c k throughout, sup- 
ported by horizontal beams 



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d \ ly k I 'in'-r 



ii-I lATTFR riN wi^r. 3 



Bats d- iSaLfc ?.°-- 



Stretching between t h e 
counterforts, spared ac- 
cording to the calculated 

earth pressure. The slab is 
rein forced horizontally and 
vertically on both faces with 
f-in. and J-in. bars from 
4.1 in. to 12 in. apart, and 
is well provided with weep- 
holes. The horizontal 
beams are specially de- 
signed to resist the canti- 
lever action produced by 
the downward pressure of 
the filling", and account of 
this action had also to be 
taken in designing - the slab. 
The counterforts, as 
illustrated in Fig. 7, are of 
the open braced type de- 
signed as framed canti- 
levers about the base slab 
and supporting- the wall 
slab, which resists the 
lateral earth pressure. This 
type of counterfort repre- 
sents a considerable saving 
over the solid type. The 
bracings for these counter- 
forts are 14 in. by 14 in. under the girders and 12 in. by 12 in. elsewhere, 
substantial gussets reinforced with J-in. bars being formed at all angles. As 
seen from Fig. 7, the main tensile reinforcements in these bracings all spring 
from anchor blocks in the foundation slabs, where they are hooked around 
special bars placed under the foundation beams. These main bars branch off 
into the various bracings according to the forces which have to be resisted, 
and terminate near the face of the wall with ample return hooks. Many of 

327 



^v***-**^ 



bN'Mmn fV i rs rUVVfrh ftn. H^Ur.,,..^ h-'/At^ <\3,* 



Fig. 7. Section Showing Reinforcement. 
Reinforced Concrete Bridge near Merthyr. 



CHAS. E. HOLLOW AY. 



1CQNCKETE1 



these bars are of large diameter and length, and, after being' bent to shape, 
were ereeted and secured in place by the scaffolding, which was erected 




Fig. 8. View Showing Finished Walls. 




lig. '). View Showing Girder Spans. 
Reinforced Concrete Bridge near Merthyr. 



beforehand for this purpose, and was afterwards also utilised lor concreting 
and shuttering operations. 

328 



y„ CONM PUCTIUNAl 



CONCRETE BRIDGE NEAR MERTHYR, 



cn^> 



I he foundation slab as illustrated in Fig. 6 is -'_> ft. wide undei the girders, 
tapering to i.| ft. wide a1 the extremities. The toe projects 5 ft. beyond the 
face oJ the wall al the centre and 1 ft. al the wing's. The slab varies from sin. 
to 6 in. thick, as shown, and is reinforced on both faces in both directions with 
1. -in. and ft -in. bars. Ii is supported al shorl intervals by beams running from 
toe to heel, which varj from 30 in. I>\ 12 in. to [6 in. b) <s in. The reinforce- 
ment for these beams al the 

cciilrc is shown in Fig. 7, and 
consists of 3 unit trusses 
e 1 in 1*3 placed side by side with three 
Xo. 1 ; -in. main bars in each 
truss. At the heel these trans- 
verse beams are supported by 
a main beam, which runs into 
the anchor blocks, and at the 
toe they support a secondary 
beam, which carries the outer 
edge of the slab. The upward 
earth pressure at the toe tends 
to lift this beam and the slab 
off the transverse beams, and 
special reinforcement is pro- 
vided to resist this action. 

The abutment walls were 
designed to resist earth pres- 
sures in accordance with Ran- 
kine's theory, taking the 
weight cf filling as 100 lb. per 
cu. ft. with an angle of re- 
pose of 36 . The resultant 
force on the foundations was 
made to fall within the middle 
third, and the factor of safety 
against overturning was cal- 
culated to be not less than 2. 
The girders were not assumed 
to assist in resisting the over- 
turning forces, although their 
dead weight was taken into 
account when finding the re- 
sultant force on the base. 

A stream flows into the 
canal near one side of the 
canal abutment, and a wing wall, 36 ft. long, is provided to retain the embank- 
ment at this stream, as shown in Fig. 1. This wall is 19 ft. 9 in. high where 
it is bonded into the canal abutment, reducing- to 14 ft. at the other extremity. 
It is very similar in design to the other walls, but the counterforts, which are 
9 ft. apart, are solid, 8 in. thick, as it was not found economical to construct 
counterforts of the braced type for this height of wall. 

329 



U «U Bracing 
Cenlre f3ay 




Fig. 10. Section of Railway Abutment. 
Rkinforced Concrete Bridge near Merthyr. 



CHAS. E. HOLLOW AY. 



[CONCRETE 



£ 



Railway Abutment. — The railway abutment embodies some interesting- 
features owing- to the faet that it will be buried up to the Rhymney railway 
formation level ^=] rz^ / ^ 



when the approaeh 
embankment to the 
bridge is made. 
From Fig. 10 it is 
seen that the verti- 
cal slab is emitted 
for the portion of 
the wall to be 
buried, thus saving 
a large amount of 
material and 
greatly reducing 
the proportions of 
the abutment 
owing to the re- 
sulting reduction in 
the lateral pressure 
on the vertical slab. 
The details of this 
abutment are very 
similar to those of 
the canal abutment. 
T h e foundation 




Pone I i 



fV- n 



d( sf>^j 



377? VWNsVW rrr7 







\2 ' n ' 



5IDE ELEVATION 



slab is 15 ft. wide 
at the centre and 
9 ft. wide at the 
extremities, a n d 
varies from 9 in. to ^//sswv^ 
6 in. thick, sup- 
ported by beams as 
illustrated in the 
figure. Cross- 
bracing is intro- 
duced in the centre- 
bay under the verti- 
cal slab to resist 
lateral forces such 
as wind - pressure, 
as this abutment is 
entirely supported 

' ' ' Fig. 11. Plan on Line CC. 

On posts lor the Reinforced Concrete Bridge near Merthyr. 

lower J-} It. of its height, these posts to be eventually buried up as described 

above. 

The Pier. — The pier, as is the case with the Other parts of the structure, 

330 



\ j, CONM UMICTIONAl' 
L«VKN(.1NKI.WIN(. — , 



CONCRETE BRIDGE NEAR MERTHYR. 



is c i \ t i\ lighl and economical design. It is well illustrated in Figs, i i and H. 
The foundation slab measures 24 ft. by 12 ft. and is <) in. average thickness, 
reinf< reed with }-in. and ,,.-m. bars, h is stiffened with beams 36 in. bj 16 in. 
in both directions. The pillar measures 14 ft. 6 in. by 6 It. It is braced 
diagonally with [2-in. by 8-in. bracings on the wider faces, and is solid on the 
oilier faces, being everywhere S in. thick except where it is reduced to 6 in. 
thick by the bevelled panels, 4 ft. wide by 2 in. deep, on the solid fates, as 
shown in the section, Fig. 11. 

At the top of the pier under the girders are two beams 30 in. by [6 in., 
connected by a heavy slab to form a bearing. 

The Girders. — The girder spans are of the Warren type, 93 ft. 4 in. centre 
to centre of bearings, and are illustrated in detail in Figs. 5 and 9. The girders 
art' 1 1 It. 6 in. deep over all and 10 ft. apart in the clear. The tension booms 




boo Cramp 



Fig. 12. Cross Section of Shuttering. 
Reinforced Concrete Bridge near Merthvr. 

are 18 in. by 10 in., and the compression boom 18 in. by 18 in. at the centre 
tapering- to 18 in. by 10 in. on the two end bays each side. The bracing-s are 
very light, the end posts being 18 in. by 10 in. and the remainder 10 in. by 10 in. 
The tension booms are reinforced with 12 No. ij-in. bars arranged in two 
sets of six, as shown in Fig. 5, the bars overlapping in such a way as to fit the 
bending moment diagram. In each case they extend 5 ft. beyond the last 
panel, which they are intended to reinforce and terminate in a return hock of 
6 in. internal diameter. Each set of six bars is bound together laterally with 
-rV-in. ties 6 in. apart except at the hocks where they are increased to t% in. 
The method of fixing this reinforcement in place is worthy of note. One set 
of six bars was arranged on wooden blocks laid on the deck shuttering. These 
bars were fixed at the correct distances apart by wedging wooden spacers 
between them. The ties were then placed on the bars and wired to them at 

33i 



CHAS. E. HOLLOW AY 



fCDMCBEXFJ 



alternate intersections with 16 gauge annealed wire. A frame of reinforcement 
was thus made of sufficient rigidity to be bodily lifted and laid in the moulds. 

The reinforcements for the tension diagonals were dealt with in a similar 
manner. As seen from Fig. 5, these bars are carried 4 ft. horizontally into the 
booms and the ends hooked at right angles, to secure the necessary bond. At 
the end joint in the top boom this bond cannot be secured, and the bars are 
anchored by hooking" over the top reinforcement of the other members and 
returning- the hooks a sufficient distance. Special attention had to be given to 
the joint at the bearing- for a similar reason. The bending of these bars was 
done cold on a bench consisting of one timber 20 ft. long and 12 in. square on 
which were mounted the necessary studs. Heavy weldless tubes to slide over 
the bars were used as levers. The reinforcements for the compression members 
were wired into units on templates. 

In each span there are 4 No. transverse wind braces 10 in. by 8 in. reinforced 
with 4 Xo. f bars and rVin. ties 6 in. apart. The bridge is also stiffened against 
lateral forces by 18 in. by 12 in. gussets connecting the diagonal bracings with 
the crossbeams. 

Owing to the possibility of settlement in the foundations the girders had 
to be constructed quite separate from the abutments and pier in such a way that 
they could be raised upon packing if necessary. As shown in Fig. 5, the main 
girders rest on lead sheets 30 in. by 12 in., § in. thick. A steel dowel 2 in. 
in diameter projects up from the bearing into a 2^-in. internal diameter tube 
bedded in the girder, thus forming a bearing free to move vertically. 

The shuttering for the girders w r as supported by strong timber trestling 
shown in Figs. 1 and 8, the verticals consisting of full timbers and the diagonals 
of half timbers. The trestling was bolted together with i|-in. bolts provided 
with plate washers, and was erected with the help of a derrick pole and hand 
winch with blocks and tackle. The largest timbers used were 40 ft. long and 
14 in. square. This trestling supported longitudinal timbers running through 
the bridge directly under the main girders, on which the shuttering w 7 as carried. 
Fig. \2 shows a cross section of the shuttering adopted for the girders. 

Generally. — The bridge was designed for a superload of 170 lb. per 
sq. ft. live and 50 11). per sq. ft. for ballast. 

The bridge spans have not yet been tested, as the approach embankment 
is not yet formed. The measured deflection of the span over the railway on 
taking its own weight when striking the slack blocks was \ in., which appears 
to show that the girders are very stiff. 

The ( oncrete for the. abutments and pier was mixed in the proportions oi 
1 bag cement (11 bags per ton), 4?, cu. ft. sand, 9 cu. It. chippings. For the 
gilders a richer concrete was used- namely, 1 bag cement (11 bags per ton), 
3^ cu. ft. sand, 7 cu. ft. chippings. Crushed pennant of very close texture was 
used for the chippings and crusher dust from the same stone was used lor sand. 
A very satisfactory concrete was obtained, which also gave an excellent lace to 
the work. 



33 2 



[ 5. IONM VIKTIONAIJ 
Ln.l.N(ilNt-l V1NI. ~J 



Till-: NEUTRAL AXIS IN A TEE-BEAM 



T — 




-* 



THE DETERMINATION OF 
THE POSITION OF THE 
NEUTRAL AXIS IN A TEE- 
BEAM BY THE AID OF 
SIMPLE GRAPHS. 



1 



By H. E. LANCE MARTIN, B.Sc.Eng. (Lond.\ of the University of Liverpool. 

The following article will no doubt te of interest to all engaged in the designing of 
reinforced concrete. 

For the proper design of a tee beam in reinforced concrete it is essential that 
the position of the neutral axis should be found. Unfortunately the recognised 
rules as issued in the second report of the R.I.B.A. and the Regulations of the 
London C.C. are somewhat complicated, and to anyone not skilled in using 
such formula? these present some difficulties. 

The experience of the writer as a lecturer on this subject more than bears 
out this statement, and he feels that a method which simplifies such is more 
than justified. 

The formula as given in the report is n, = (si f 2mr)l(2s, J r2mr) and should 
be used only when the neutral axis comes below the slab. 

w / = The ratio of the depth of the N.A. n below the floor level to the effec- 
tive depth d of the tee beam. 

, s / = The ratio of the total depth d s of the floor slab 

( ' f ' l to the effective depth d of the tee beam. 

m = The ratio of the moduli of steel and concrete = 



— ' r = The ratio of the steel area A,, to the area of 

FlG - l - the concrete b x b in the tee beam. 

Plotting- this equation for various values of r, the relation between s, and )i , is 
obtained (Fig. 2), in which six curves are indicated. Xow it is at once seen 
that any one of the particular values of r chosen for this purpose will prob- 
ably not be the value employed in any given design. Thus for a given case 
s, and r are known, but n / is unknown. Xow the relation between r and n t 
can easily be found from Fig. 2 by keeping the value of s, constant — that is to 
say, by drawing a horizontal line parallel to the value of n.., through the known 
value s n and reading off the values of n, where this horizontal line cuts the 
curves. These plotted against the various values of r give the relation between 



all values of n and r, and a series of these is indicated in Fig. 



These latter 



arc more direct in use than those shown in Fig. 2, but care must be exercised 
in not confusing one curve for another in the places where they cross each other. 
Thev have been drawn with differently dotted lines in order to avoid this small 
difficulty as much as possible. 

An example will make the methods of using these curves clear. Say 

333 



H. E. LANCE MARTIN. (CONCRE TE) 

d s =7 ", b— 105 , ^ = 44", and r = o'oo2y^, all these would be known from 
previous calculations. Then s f = 0'i$g. Xow, using- the curves of Fig. 2, follow 
hoiizontallv the value of s. along- until the curve for r = o'oo2 is reached. The 

















/ / * 






























// 








\ 








/ 






vo \ 






~"~~-~--^^ 














5 

— 




57o- "" 




C/J 








> 


V 






\ 










\ 






'$>• 








r~ 








































1 


\ 



i0 
o 



's jo sanjBA 

required point lies on this horizontal line between the curve for r 0*005 ani ' 
the above curve. Interpolate and read off on the 11 , scale by following- the 
vertical line down through the estimated point. Doing this we find that 
??, =0*28. The process is indicated by arrows in the figure. 

334 



» eON.ML'lKTIUNAL 
AkMilNKF.kMNd — , 



THE NEUTRAL AXIS IN A TEE BEAM. 



Now, iis'ihl; Fig. 3, follow up vertically the given value <>! r until it reaches 
the curve for s 0*2; the required curve lies between tins and thai l<" \ o*i. 
Interpolate and read oil the required value of n, by tracing the horizontal line 
drawn through the intersecting point. In this case >/, 0*27. B3 actually 
calculating from tin- formula n, 0*26, which shows thai tin- above values are 
quite near enough lor practical purposes. If, however, this hitter result is 

t 




'ii jo sanity 

required from the curves it can be obtained by drawing" the horizontal line in 
Fig. 2 through the given value of s., so that it cuts all the curves and noting 
the values of n t corresponding- to the intersection points; these values plotted 
against the values of r will give the exact curve which in the method above was 
only estimated. Now from the given value of r — viz., 0*0273 — the correspond- 
ing value of n r can be read off directly on this new curve — viz., C268 — the same 

335 



H. E. LANCE MARTIN. 



[CDNCBET FJ 



a> given by calculation. Another very useful property of Fig. 2 is that by 
joining - all the minimum values of n. together a straight line is the result, 
which passes through the origin. Now the minimum value of n ! is obviously 
when the neutral axis coincides with the underside of the floor slab, in other 
words when n r = s. r Looking at Fig. 2, this is at once seen to be the case; 
hence bv drawing this line it can be determined whether the neutral axis is 
below the floor slab or not by noticing whether the estimated point lies with 
respect to this line. 

This can be shown also mathematically by differentiating the equation 

_s, -r z,mr an( j determining the minimum value n l thus, 

dn,_ 2s l (2s l + 2mr)-2 (sr + 2wr) 
ds, (2s,-\-2tnrY 



putting the numerator =0 we have that s t — v wV 2 + 2wr — mr, which if sub- 
stituted in the orig-inal equation will give the required minimum value 
of n r This latter step, however, need not be done, as it will be seen that 
the value of s, found above is exactly the same expression as that given in the 
report for n t when the neutral axis falls within the slab, hence $ ( = 
<s/m 2 f z + 2mr — mr = n n the same result as obtained by considering the graphs. 

Finally by plotting the various values of r in Fig. 2 against the values of 
n. obtained bv noting the points of intersection of the curves and the slanting 
line, the relation between these is found when s / = n / or, in other words, the 
position of the neutral axis is known with regard to r when this falls inside the 
floor slab. 

Example 1. — Say d s = si", ^ = 64", d=i$^", and 7 = 0*00675. Then 
$, = 0*355 an d fr' om tnc curves ^ = 0*36, .'. 71 = 0*36 x 15*5 = 5*6, showing that 
the X.A. in this case is just on the inside of the slab, which can be seen from 
Fig. 2, the intersection point being nearly on the limiting line. 

Example 2. — Say d s = 5i", b = 8i", d = 22", and r = o'on. Then $, = 0*25 
and from the curves ra v = o*47. The intersection point ^ ( // /// /// ///yjh'aT\ 
in this case is well below the limiting line, therefore the 
X.A. should be below the underside of the slab, its 
actual position being n = 0*47 x 22 = io"3". 

Example 3. — Say d s =6", b = 6o", d — 21", and r = 
o"oo2y Then £, = 0*285 and from the curves n. f = o'2^. The intersection 
point is, however, above the limiting line, therefore the curve given in Fig. 3 
must be used. The position of the N.A., however, using ^, = 0*24, works out 
to be 0*24x21=0*285, which is inside the floor slab. Now, using the proper 
curve n f = 0*235 therefore n — 4'cj, a result very near to that given above. It 
is to be noticed thai for the purpose of the equation n , = (s ^ + 2mr) /(2s / + 2iur) 

when s f — n.,— - that the above value of s / — viz. ,=0*285 — is incorrect, the proper 

d 
value being sj =0*235, which is the same value as found above. In other words, 
when the X.A. falls within the slab the ratio of n to d must be used (see Fig. 4), 
instead of d v to d. 



336 



Fig. 4. 






'j-CONyi'UlKTlONAll 



REINFORCED CONCRETE FOR GAS WORKS. 




REINFORCED CONCRETE IN 
THE NEW GAS WORKS AT 
KEILEHAVEN, ROTTERDAM. 



We arc indebted for the following particulars and photographs to Mr. H. C. Sissingh, the 
Director and General Manager of the Rotterdam Gas Works.— ED. 



Reinforced concrete has entered very largely into the construction of the 
buildings tor the new gas works at Keilehaven, Rotterdam. These works 
were started in 191.3, and are so arranged as to allow for future extensions. 

In view of the unstable soil in Rotterdam it was necessary to place all 
the buildings on pile foundations, and in consequence of the surface water 
level the tops of the piles are brought up to a point 3*25 m. below the 
floor. This has led to the provision of watertight cellars to the greater part 
of the buildings, in order that they could be used, in connection with the 
installations, for gas mains, conduits, or other apparata. These cellars are 
also constructed of reinforced concrete. 

Where there was no necessity for underground accommodation the founda- 
tions are built solid with reinforced concrete walls or columns and ties. This 
is shown in Fig. 1, indicating the foundation of the retort house and the coal 
bunker house annexe. 

Reinforced concrete was also used for the underground tar and ammonia- 
water tanks, and for various floors, thus forming the main constructional 
material for a portion of the buildings of this new water-gas plant. 

The accommodation of this portion includes a cellar, through which the 
main conduits run, an exhauster house, a blower-room, and a flat rectangular 
water tank for cooling off the wash-water. This building can be seen in the 
centre of the background in Fig. 4, and it is also just indicated in the left-hand 
corner of Fig. 5. The panels between the external reinforced concrete framing 
where not utilised for windows are filled in with brickwork. 

Special mention should be made of the foundation of a gasholder (of 
75,000 cu. m. capacity), which is on the ordinary tank system with a flat 
bottom. The tank itself — 54 m. diameter and 10 m. high — is of iron, but it 
rests on a bed of reinforced concrete 0*25 m. thick, having a pile foundation. 
This bed is provided with a surrounding wall 1*65 m. high of the same 
material, and the space between this wall is filled up with sand. The sand 
has been covered with a laver of coke breeze mixed with tar, on which the 
iron tank rests. 

The principal reinforced concrete building is the coke house, which has 
been executed entirely in this material. Figs. 2, 3, and 4 are various illustra- 
tions of this structure, whilst Fig. 5 shows the building during construction. 

c 337 



REINFORCED CONCRETE FOR GAS WORKS. 



[CONCRETE] 




c 
< 
0) S 



I- H 

3 - 



o 



03 O 



ffi 



8 °_ 



0) u 

Pi pi 



338 



' g T COWS I VI JCnONAp 



REINFORCED CONCRETE l<ott CAS WORKS. 



[ n pi«-, | ( ,,n the right, the retort house is shown with it s horizontal 
furnace chambers. The hoi coke is discharged from the chamber ovens and 
falls into open trucks, consisting of a framework of heavy iron bars. Hiese 
trucks are conveyed by humus of a locomotive i<> the coke house (Figs. 2 




Fig. 2. Reinforced Concrete Coke 1 House. 
Reinforced Concrete at the New Keilehaven Gas Works, Rotterdam. 



and 6). The capacity of these trucks is 8 cu. m., or 3,000 kg. by weight. 
The truck on arriving at the coke house is placed on to a platform and then 
lowered into a concrete trough, where the coke is quenched with water. The 
resulting steam escapes by a high concrete shaft Fig. 4 (a) and the funnel (b) 
connected with same. 

c 2 339 



REINFORCED CONCRETE FOR GAS WORKS. 



1CDNCKETE1 



As soon as the coke is quenched the truck is again placed on the moving 
platform, and this, when raised to its highest point, is tipped with the truck 
into the chamber marked (c), Figs. 2 and 3, from whence the coke discharges 
into the bunker (J), Fig. 4. 



38 2S »> 



wmm 




Fig. 3. Reinforced Concrete Coke House with Shaft, 
Reinforced Concrete ai the New Keilehaven Gas Works, Rotterdam. 

This building also contains the coke breaking and screening arrangements,, 
and there are lour bins (or storage bunkers), each containing coke of different 

34° 



j,con.vh.mic-honai. 

t\ l.N( .1 Ml.K'lNt. — , 



REINFORCED CONCRETE FOR GAS WORKS. 



sizes From these bunkers the coke can be discharged in various ways, 

of which isb 3 means of tip wagons moving on a platform (Fig. 3) "'» connection 
with the bridges shown on Fig. |, from whence the wagons are emptied from 
a height of 7 m. There are also devices for discharging the coke into bags 







;/ 




a -z 

o s 



c - 

rt ~ "2 

<u i. — 

in - ■• 

t- > 

c- M 



o 



o 



for sale in town, into railway wagons placed under the gate, and into small 
trucks for the supply of the water-gas plant. 

Some other particulars follow here : — 

The dimensions of the building- are 12 by 6'20 m. 



3 + i 



REINFORCED CONCRETE FOR GAS WORKS. 

Contents of bunker (d) = ~2m\ 

Contents of the four bunkers (c) = 456m 3 . 

Total weight of lift cage, wagon, and coke± 12,000 kg. 



fCQNCHETEi 




342 



Fig. 5. Coke House in course of construction. 

|.,,m, ,11 11 m mi. Nk\V Ki hi iiavi.n (.as Works. ROTTERDAM. 



fg r OONSTU'IICTIOMAD 
Lf^£MGIMt.L-mNG --J 



REINFORCED CONCRETE FOR GAS WORKS. 



Mu lift engine is erected above the lilt shaft in the engine-room [g). Th< 
hoisting 'motor for the lift has a capacity oi 30 h.p. The weight of the lift cage 
and 1 1 the coke wagon is balanced 1>\ heavy counter-weights, which move in 

the shall (//). 

The inclined bottom-planes of the bunkers [e] are sheathed out with hard 
tiles, which can be renewed after being worn. 

The bottom-planes of the bunker (</), in which the unbroken coke is 

dis< harged, are sheathed out with iron plates. 

The capacity of each break- and screen-apparatus is 34 m*. coke per hour. 

The building expenses have amounted to : — 

±hfl. 41*000 for the building (excluding foundation). 

±hfl. 35000 for the whole mechanical arrangement. 




Fig. 6. Showing Discharging of' Coke from the Chamber Ovens into Open Trucks 
Reinforced Concrete at the New Keilehaven Gas Works, Rotterdam 



3+3 



RECENT BRITISH PATENTS. 



1CQNCRETEJ 



RECENT BRITISH PATENTS 
RELATING TO CONCRETE, 

We propose to present at intervals particulars of British Patents issued in connection 
ivith concrete and reinforced concrete. The last article appeared in our issue of 
April, 1915.— ED. 

Culverts, Tunnels, etc. — No. 7120/14. Edmond Coignet, Ltd., 20, Victoria Street. 

London. Accepted April 22/15. — The invention comprises improved reinforced concrete 
linings, such as described in Specification No. 12,970 of 1911, and while particularly 
suitable for lining a mine gallery, culvert or tunnel, can be used with equal advantage 
for constructing a tube or tunnel in place of ordinary circular metal or concrete or 
similar tubes at 
present e m- 
ployed for ordi- 
nary purposes. 

A c c o rding 
to the invention 
a number o f 
longitudinal and 
transverse inde- 
pendent reinforc- 
ing bars, bent 
o v e r towards 
their ends so as 
to form hooks, 
are employed, 
the return por- 
tions of the latter 
being embedded 
in the concrete, 
leaving project- 
ing loops or 
eyes; there are 
pockets at the 
ends and sides of 
the concrete for 
the reception of 
the looped ends 
of the reinforc- 
ing bars. 

T h e s e g - 
mental numbers 
(ij are made of 
a w i d t h and 
length that will 
enable them to 
be conveniently 
handled a n d 
m a n i p u lated, 
and of a form 
thai e -1 n 1) e 
readily moulded ; 
upon their meet- 
ing faces keying 
spaces are pro- 
vided into which 
t h e projci ting 

hook's formed by the main reinforcing members enter, the projecting hooks being 
coupled together by means of metal bolts, etc. 
344- 




j T 00N>TPlKT10NAi;i 
l\ 1M.IM 1 KM NO ^.' 



RECENT BRITISH PATENTS, 




Accepted March 18/15.- 



The main reinforcing bars 2, 3, 4, 5, for 1 1 1 1 - unit i, are bent round at th< outer end* 
to form hook-like loops (2a, \a, etc.), the return ends (2*, etc.) being embedded in th< 
concrete. Through the projecting loops thus formed, gudgeon or uniting pins or bolts (6) 
m .o be passed, leaving the pockets or openings (7) free for the cement grouting to b 
run | 1V , h therein and to pass through the spaces (8) so as entireh to lill and close the 
spaces between each pair ol unil members, such as 1, i", \'\ thereby forming not onlj 
;l complete joinl bu1 .1 means for holding in position the gudgeon or dowel! pins or bolts 
(i,), the outer surface of the pockets being finished to suil the configuration of the inn< 1 
and outer edges or faces of the unil members. 

Tlic bars 2, ,, 4, 5, are held in position by means of stirrup members (9) and cross- 
bars r IO ) i uniting these 10 the main members b\ binding wire or other ordinar) means 
of attachment to retain them in position until the concrete or cement surrounds them 
when poured into the casing or mould in which cadi unit is constructed. 

Longitudinal connections are made 1>\ means of the loops 20, 30, etc., and the cross 
connections In means of similar loops (i'oa) placing through these latter loops connect- 
ing pins (11)/ to hold them in position, leaving pockets and spaces (12) for the cement 
grouting to be run therein so as to bond the different segments into position and to 
build up the different sections of the tube to make the length of circular gallery or 

tunnel desired. 

The meeting ends of the different units are arranged so that the joints are broken or 

alternated in the manner shown in Fig. 3. 

Reinforced Concrete Buildings. —No. 10639. C. M. Burnett, St. Catharine's, 
Clifton Road, Regent's Park. Shirley, Southampton. Accepted March 18/iS. — In 
accordance- \v i t h 
this invention build- 
ing's are for m e d 
with a reinforced 
concrete framework 
consisting p r i n - 
cipally of matured 
reinforced concrete 
beams, columns, 
slabs, etc., pro- 
vided with project- 
ing reinforcement 
by means of which j," 
the various parts 
are connected to- 
gether, the joints 
being permanently 

fixed before completion by filling in the space 
between the concrete ends with Portland or 
other cement. 

A corner foundation base stone (a) carries 
tubes (a 1 ) into which fit the projecting rein- 
forcing bars (b l ) of the corner column (b). These 
tubes (a 1 ) are embraced by a metal bar (a 2 ) which 
has projecting eyes (a?) into which are fitted the 
turned-down ends (ai) of reinforcing bars (as) for the foundation beams. Breeze or like 
slabs (r), and a partition slab (c l ) at an intermediate column (&5), Figs. 4 and 6, are 
fitted between the columns, and cross bands or wires (d), secured to the blocks, are 
provided with projecting down-turned ends which hook into loops (b 2 ) projecting from 
the columns. In the case of the corner column (b) a loose reinforcing bar (fa) may be 
carried by the stirrups (& 2 ), and the strips (d) are hooked into loops (b*) passed round 
the rod. 

Fig. 19 shows the manner in which a matured reinforced concrete floor beam is 
connected to an intermediate column with projecting portions (bs) forming a T-seetion as 
in Fig. 4; the ends (ai) of the beam-reinforcing bars are turned down and hook into 
eyes cast in the column and passed round the reinforcement. 

After the various units have been assembled in this manner they are rendered mono- 
lithic by casting cement between them. 

3+5 




ngi5 



"Fifc-5 




life! 

Reinforced Concrete Buildings. 



RECENT BRITISH PATENTS. 



1CQNCBETE1 



Fig. 15 shows a reinforced concrete stairway, provided with wood or concrete 
nosings (h l ) attached by metal bands (h 2 ) to a longitudinal reinforcement bar (In), which 
is exposed at the angle of each step to form an eyelet for the stair rod. 

Joints are made in the columns by metal sockets surrounding the reinforcement ; 
they project from the surface of one part and engage corresponding recesses in the other. 

Moulds for Walls .— No. 9193 14. W. J. Mills, Church Road, Whitchurch, Somer- 
set. Accepted April 8/14. — This invention provides an improved form of mould for 
casting hollow walls in situ, the 
feature of the invention being the 
cam plate catch for connecting the 
shutters to the cavity block. 

The cam plates (2) are carried 
by hand-levers (3) pivoted to the 
head (9) carried by the cavity block 
(8), and engage catches (4) carried 
by the shutters (1) which are 
strengthened at the ends by metal 
plates (6) fastened to battens (7). 

The cavity block (8) carries 
wheels (15) on its under side to facili- 
tate the traversing of the mould, and 
is divided vertically at the line (10) 
so that it may be withdrawn from 
the bond bar (11). The wheels run 
upon a detachable rail (16) carried 
by a wooden bar (17) which rests 
upon the bond bars (11) in the cavity of the wall. 

To assist in separating the shutters after the cam plates have been turned to release 
the catches, springs (14) are provided between the shutters and the head (9). A 
wooden cramp is provided to fit over the shutters of the mould between battens (19), and 
both shutters and cavity blocks are covered with a protective layer of sheet zinc, which 
serves to form a smooth wall surface. 

Reinforcing Bars. — No. 10353/14. Patrick Henry Kane, 63, Cleveland Avenue, 
Buffalo, Erie, New York, U.S.A. Accepted February 11/ 15. — The present invention 
consists essentially in a reinforcing bar of cruciform cross section for use in beams, 
columns and other forms of reinforced concrete work. 

Each bar may be provided with anchoring means in the form of projecting ribs or 




Fie 2 



FIG A- 



Moulds for Walls. 





[ectively prevent any slipping or 



Reinfor* in<; Bars. 
corrugations, or grooves may be provided so as to e 

displacement in the concrete. 

Each of these bars consists of a core or body (3) and four or more longitudinal 
webs (4) extending outwardly from the body in different directions and provided with 
laterally-projecting anchoring heads, flanges or enlargements (5) which extend beyond 
both sides of each web. 

34 6 






RECENT BRITISH PATENTS. 





f&fcsp£&$i& 



Jt 



A 



FlCi 4- 



F/& b 



Reinforced Concrete Floors— No. [7561/14. II'. G. Shipwright, 218, Well- 
meadow A'ci/i/, Catford, London, S.E., and F. R, Minim. Accepted March 4/15. This 
invention comprises an improved floor of the type built up of beams made of burnt 
clay or like blocks and reinforced concrete without employing any temporary supports. 

The bricks or tiles are approximately inverted V or arched cross-section, so that 
When a number of these tiles are 

arranged end to end and connected 
by means of reinforcing rods em- 
bedded in cemenl in longitudinal 

holes or grooves in the tiles to form 
a beam or slab, and when two of 
these beams or slabs are placed side 
by side in contact with each other an 
approximately V-shaped space is 
formed between the beams. 

The itiles (.1) have sloping or 
arched sides, and dovetail grooves 
{a) are formed in the sides and bases. 
A number of these tiles are placed 
end to end, resting upon their flat 
bases, and connected to each other 
to form a beam or slab by embedding 
metal rods (B), or bars or angle 
irons, in concrete or similar material introduced into grooves (B) formed in the sloping 
or arched sides and at the apex of the tiles. The beams are ready for use as soon as the 
concrete has set hard in these grooves (B). The tiles may be hollow as indicated in dotted 
lines in the drawing. 

In a modified construction, Fig. 6, the tile beams are spaced some distance 
apart, and shallow tiles (C), shaped about as shown in the drawing, are arranged in the 
bottom of the approximately trough-shaped space between adjacent beams before the 
space is filled in with concrete, the tiles resting upon the sloping sides of the beams. 




Reinforced Concrete Floors. 



347 



NATHAN C. JOHNSON. 



CONCRETE] 




^ 



MECHANICAL DISINTEG- 
RATION OF DEFECTIVE 
CONCRETES. 



J'- 



Demonstrating Certain Disruptive Crystalline Actions, 
which have their inception in the Capillary Pores* 

By NATHAN C. JOHNSON, 

Consulting Engineer, New York City. 

Second article of series. — In reprinting these articles we "would state that the opinions 
expressed are those of the author, and the Journal as such does not necessarily associate 
itself with the conclusions arrived at. The articles are reprinted by the courtesy of the 
"Engineering Record, " U.S.A., and the illustrations have been placed at our disposal by 
the author. — ED. 

When sea water, or even fresh water, is brought into contact with the cement matrix of 
concrete, solution to a greater or less extent adds new compounds of indefinite nature. 
When such waters are carried to the interior of a mass of concrete by the capillary 
action of minute pores, the limitations to quantity imposed by the size of the pores 
result in the production of super-saturated solutions of ithese dissolved materials. But 
super-saturated solutions speedily crystallise on reaching a certain density, with the 
result that there are exerted on the matrix of the concrete powerful disruptive stresses, 
the effects of which may readily be traced by means of the microscope. These stresses 
may even exceed the strength of the concrete, with the production of local disruptions 
which later become general. To differentiate these disruptions from other purely 
chemical actions that may cause the failure of concretes, they have been designated as 
" mechanical disintegrations " — a designation which, it is believed, the demonstrations 
of this paper will justify. These are some of the secondary effects attributable directly 
to the presence of entrained air in concrete, the primary effects of which were pointed 
out in the preceding article (issue of June). 

It should be understood that while these demonstrations are unusual and to a 
certain ■extent startling, they relate to defective concretes, and are quite without 
prejudice to the successful uses of concrete in sub-aqueous structures in all parts of the 
world. One of the primary objects of this research has been the production of concrete 
thoroughly capable of withstanding the action of waters which have heretofore caused 
trouble; and in any such quest it is essential that all of the actions involved should be 
thoroughly understood. 

It is probable ih.it many of the vexatious faults of concrete construction of all classes 
are due as much to physical as to chemical causes; and, secondarily, to a combination 
of physical and chemical causes. In sea-water construction, especially, it is probable 
ili.it the defects which induce failure lie primarily not so much in the cement, providing 
cement of proper quality he used, as in the improper proportioning of aggregates, or in 
poor mixing, or in a combination of the two. 

CONCRETES TO BE STUDIED. 

In Fig. 7 .are given photomicrographs of the four concretes which are to he in- 
vestigated with a view to determining causes of such failure. These photographs were 
taken ,-,t low power in order that as much of the surface as possible, the inter-relation 
348 



y.l'ONMVIK TIONAi: 
< - l NGIN1 l RING — d 



THE MICROSCOPE IN THE STUDY OF CONCRETE, 



"t aggregates, and, particularly, ili<' prevalence <>l pores in the matrix might !)<• made 
plain. 

In interpreting these photographs, i 1 should be remembered thai .ill <<f the la 
irregulai white patches with dark bordeVs are sand grains; thai each <>l the black 
patches, or irregular black streaks, is a hole 01 .1 deep crack, and thai the white materia] 
between the -mil grains is the matrix, of more 01 less hydrated cement. K it not 
significant thai no two ol these sand grains are touching ? And is ii nol significant also 
ami confirmatory ol what has befon been said, that between the •-and grains in even 
photograph lie smaller grains, too small to be sand? By using a higher magnification 
with the microscope, these latter ran very easilj he proved to !»«• groups of unhydrated 




(a) Steel Pier, Atlantic City, N.J. (b) Spillway of Dam, Ithaca, X.Y. 

(c) Dock Wall, East River, New York. (d) Pile Cap, New York Harbour. 

Fig. 7. Investigation of Concretes discussed in this article. 

Magnification, 20 diameters ; black spots are holes. 

The Microscope in the Study and Investigation of Concrete. 

cement particles, a proof to be demonstrated fully and conclusively in the final article 
of this series. 

PORES IN MATRIX. 
But the feature to which present attention is most strongly directed is the 
prevalence of black spots in the cement matrix. Each of these is a hole, or pore, of 
indefinite direction and extent. Further, as each photograph shows the features of a 
random section in a random specimen from the structure in question, it is probable that 
practically the whole of each of these structures is literally honeycombed by millions of 
tiny pores. 

349 



NATHAN C. JOHNSON. [C0NO3ET£ 



Although the presence of such pores in concrete has long been known, it is a 
question whether or not their prevalence and the damage they may cause has been 
recognised. The seepage of water into pores and the disintegrating action of frost have 
been remarked by a number of observers, but, so far as the writer is aware, the really 
serious extent to which such actions may operate has not been appreciated, the inferential 
assumption, at least, being that they are confined to surface layers. On the contrary, 
however, it seems probable that these actions operate beyond the surface layers, to a 
depth dependent upon the degree of porosity of the mass. 

Such a statement requires rigid proof. As a first step toward it, consider what must 
be the state of affairs in a concrete as full of tiny pores as the concretes under examina- 
tion would seem to be. 

CAPILLARY ACTION. 

The phenomena of capillarity — exhibited, for instance, by a tube of hair-like 
diameter of bore, or by a lamp wick — are well known. The smaller the bore of the tube, 
or the closer the weave of the wick, within certain limits, the greater will be the 
capillary effect and the higher will the liquid rise. 

It is probable that the pores of the concretes under examination are all within the 
capillary range and well adapted to aid the entrance of liquids in the mass. Further, 
the phenomena of absorption and adsorption may aid such entrance, transferring the 
liquid through semi-solid barriers to other capillary passages beyond until the entire 
mass has become thoroughly permeated. 

Under such conditions a number of disintegrating actions, in addition to that of 
frost, are possible. To take one of the most obvious, consider the results of contact 
between a stronglv saline, sulphated water and steel reinforcement embedded in concrete. 
Of all natural waters, saline solutions are the most corrosive of iron and steel ; and 
because of the progressive nature of such corrosion, a single point of attack soon results 
in the affection of a large area of the material. Ferrous sulphate and ferric chloride are 
formed, parts of which, in combination with the oxygen entrained in the concrete, or in 
the entrant water, break down into Fe O s xH 0, or common rust, with an enormous 
increase in bulk. Destruction of reinforcing steel is a sufficiently great evil, but when 
there is added to it the actual disruption of the concrete by which it is surrounded, 
collapse of the structure is to be expected. However, the existence of such action is 
dependent upon the continuity of the capillary pore and upon the existence of a point, or 
of points of attack, on the surface of the steel. Extended experiments along these 
lines show that where proper contact is had between the cement and steel there is little 
liability to corrosion. 

UNHYDRATED CEMENT. 

But although frost action and corrosion are often important factors in the success 
or failure of under-water concretes, other more obscure physico-chemical actions are 
properly the subject of this present investigation. As in previous papers, the microscope 
will be used to furnish visual evidence in regard to doubtful or conjectural points. 
Abstruse chemical questions will be avoided, as far as possible, it being preferred 
herein to regard cement only as a physical material available for structural purposes, 
rather than as a chemical complex capable of giving certain reactions under specified 
conditions. Such problems as the latter are the province of the chemist, rather than of 
i he engineer. 

It was stated in the previous article that all concretes, regardless of age, contain a 
considerable percentage of unhydrated cemenl particles, usually in groups or lumps. 
Su< h groups are shown in Fig. <s, high-power photomicrographs of the foui concretes 
whose general characteristics were shown in the low-power photographs »>f Fig. 7. 

It will be seen that all the photographs exhibit the same characteristic group- 

35° 



A r twn?m.Viil'K?^3 THE MICROSCOPE IN THE STUDY OF CONCRETE. 



structures. Especial attention is called to (< I, Fig, 8, nol onl) as an unusual photograph, 
but also because it shows a single particle oi whal is apparent 1) cemenl clinker eute< 
Needless to say, this particle Ins remained quite unaffected b) water, despite the 
passage ol years, although the concrete from which was taken the sample in which 
this relativel} large piece lies was placed under watei 3 1 years ago, when fine-grinding 




(a) Spillway of Dam. Ithaca. N.Y. (b) Pier at Atlantic City. N'.J. 

(c) Dock Wall, East River. New York. (d) Pile Cap, New York Harbour. 

Fig. 8. Unhydrated Cement Particles ; magnification, 200'diameters. 

The Microscope in the Study and Investigation of Concrete. 

was almost unheard of. This of itself is a very significant comment on the relative 
values of fine and coarse grinding. This is the only concrete so far examined by the 
writer in which so large a piece of clinker has been observed. 

PART PLAYED BY UNHYDRATED CEMENT. 

It now becomes necessary to conjecture the part such lumps play in the matrix of 
partially hydrated or wholly hydrated and set cement lying between the aggregates, if 

35 1 



NATHAN C. JOHNSON. 



(CONCEPT] 



water is later brought to them by capillary pores. Necessarily, these lumps form spots 
of low mechanical strength, but it is possible in a defective concrete that such may be 
their least objectionable feature, for in that capacity they at least form .an integral part 
of the rigid mass. But if hydration is brought about by the means above outlined, a 
new set of reactions is necessarily set up, with the formation in the very heart of the 
matrix of new compounds of uncertain nature and larger space-filling value. (H. S. 




Fit 



Shear Planes " or " Strain Bands," Pile Cap, New York Harbour; magnification, 200 diameters. 



Spackman, Cement Age, August, 1908; Feret, " Annales des Ponts et Chausses," 1892, 
II. p. 93.) But if this action takes place, and if compounds are formed such that 
tremendous disruptive forces are exerted on the matrix, it may reasonably be expected 
that their effects can be detected even short of actual fracture. In the softer metals, 
such as babbitts, which in texture are not unlike the cement matrix of concrete, 




I'm. 10. Further Examples of " Shear Planes " or " Strain Bands." 
The Microscope in the Study and Investigation of Concrete. 

incipient failure leaves traces known as " shear planes," or " strain bands," which are 
very distinctive. In Fig. <) are shown such " shear planes " in the oemen.1 matrix, witli 
several unhydrated cemenl groups near by, in a proximity highly suggestive, ii not 
wholly convincing. The pore in this instance ma} be the fissure at the side of the 

sand grain at the left. Fig. 10 shows two other such shear planes in another 

specimen. 

352 



n;cw.vrem-naNAi.| THE MICROSCOPE IN THE STUDY OF CONCRETE 

l*i FJMUIN11 PING —J 



■ CJMIUNhr.Rl 

ACTION OF SALTS CARRIED BY SEA WATER. 

This suggestion as to the origin "I these sheai planes is made tentatively. Their 
existence is known beyond doubt, but the nature 01 causes oi the forces which gave 
rise t them is solelj a matter ot conjecture. There are other pin siww bemical actions, 
not attributable to the hydration of lumps of cement, which might, with equal 
probability, be responsible 

Foi instance, when a tin) pore lias sucked up its fill of sea water, what becomes of 
that water? It can hardly be expected to remain in situ as so much sea water, until the 
end ot time, for it is loaded with chemically-vigorous salts. Absorption and adsorption 
must affect it, both qualitatively and quantitatively. First of all, it dissolves as much 




Fig. 11. Matrix Cracks radiating from a pore: Pier at Atlantic City. 
Magnification, 160 diameters. 

The Microscope in the Study and Investigation of Concrete. 

as possible of the matter with which it is in contact. When saturated, it deposits in 
solid form, and possibly with increased bulk, the salts it holds in solution, generally 
with the result that the concrete in the vicinity is at least softened, if not wholly 
disintegrated. This softening is well known and has been often commented upon. 
(Taylor and Thompson, "Concrete, Plain and Reinforced," page 310; H. S. Taft, 
Cement and Engineering News, May, 1914, page 126; U.S. Bureau of Standards, 
Bulletin 12, page 100.) 

In the progress of such an action, it is reasonable to expect that a pore would be 
the starting point of any disintegration. Such an expectation is justified. In Fig. 11 
is shown a plane cut across a pore (indicated by the black spot) ; and radiating from this 
d 353 



NATHAN C. JOHNSON. 



ICQNCBETEJ 




Fif*. 12 (a). Front and rear of Defective Buttress Wall at Pittson, Pa., 

being disrupted by crystalline dikes. 
The Microscope in the Study and Investigation of Concrete. 



pore are >w less than six fractures, with probably others in different planes which are 
not seen. The fractures can readily be traced because of their aimless wanderings 
closely resembling creeping-cracks in a sheet of glass. It should be noted that these 
fractures are quite distinct from the polish scratches, which go straight across the 
photograph. 

CRACKS REPRESENTATIVE, NOT UNUSUAL. 

If this were an isolated 
case, its value might verv 
properly be questioned. On 
the contrary, it is highly 
characteristic and representa- 
tive. Of all the very consider- 
able number of defective con- 
cretes so far examined in the 
course of this research, 
whether submerged in fresh 
water or in sea water, not one 
has failed to reveal the features 
of incipient disintegration here 
noted. Nor need the concrete 
be wholly submerged. But- 
tress walls exposed to ground 
seepage show these features to a marked degree. Magnify the actions indicated in 
Fig. ii a few hundred times, and there is realised a condition of actual, visible disinte- 
gration similar to that shown in (a) Fig. 12, where the tiny fracture has become a large 
crack filled with crystalline matter that sticks out a quarter of an inch or more from 
the face of the wall. And in (b) of the same figure is made evident the cause of this 
disintegration. As can clearly be seen, this wall is but a shell of poorly compacted and 
almost uncemented stones, into which the ground water has the freest of access. No 
wonder that the grouted face shows evidence of the decayed body. Each failure results 
from determinable causes ; 
and this case is but further 
evidence that in most instances 
the causes have their origin in 
the wilful abuse of go d 
materials. 

It is quite possible with the 
data already in hand, and with 
more accumulating daily, to 
multiply similar instances of 
incipient disintegration to a 
very considerable length, but 
two cases more should hen' 
suffice to bring home to engi- 
neers a realisation of the 
actual existence and potency 
of crystalline action similar to those noted above 



% r ^ ^jLm 




Fig. 12 (b). Front and rear of Defective Buttress Wall at Pittson, Pa., 

being disrupted by crystalline dikes. 

The Microscope in the Study and Investigation of Concrete. 



PROGRESS OF CRYSTALLISATION. 

In Fig. 13 is shown a long crystallising deposit, or dike, radiating from a pore. 
The process of its formation is not hard to picture. In the beginning the pore 
sucked up the sea water, loaded with its various salts. In the manner before out- 

35 + 



& 



msemuai 77//.; MICROSCOPE IN THE STUDY OF CONCRETE. 



-CON 
F^M(ilM.l-.WlMi —J 




lined, the watei content was diminished, with 
resultant concentration of solution, until its dis- 
solved salts crystallised, possibly while the con- 
crete was yel comparatively new. Room had to 
b e made for these crystals, so that a tiny fissure 
in the weakest material, i.e., the cement matrix, 
was formed. But surfaces close together, as were 
the sides of this fissure, act as do capillary pores, 
so that a fresh suppl) of water brought by the 
pore was sucked into this fissure, where its salts, 
in turn, crystallised, wedging the fissure yet fur- 
ther along and wider apart, with the formation, 
by repeated crystallisation, of a hard dike of 
foreign material in the space thus provided. This 
process was repeated again and again, an inde- 
finite number of time-, until the supply of cry- 
stallising salts was stopped in July last by the 
removal of the specimen from a beam beneath a 
pier at Atlantic City. 

This dike, like all others of its kind, mean- 
ders through the matrix, never crossing a piece 
f aggregate, but keeping to the weakest part of 
the concrete. At the end near the pore, where 
the crack began and where the wedging was most 
often repeated, the dike is the widest. This por- 
tion shows black in the photograph, indicating a 
surface out of the focus of the microscope. The 
dike itself at this place and the crystals in the 
pore have either been torn out in polishing or 
have been dissolved out by too great supplies of 
fresh water, or they may have become loosened 
by drying and fallen out. In any event, they are 
gone, but the place where the dike lay is plainly 
seen. The rest of the crystalline filling stands out 
boldly, because it is stronger and harder than the 
matrix which it has crushed. 

As stated before, this action is not necessarily 
confined to defective sea-water concretes. Fig. 14 
shows two similar radiating dikes, with the be- 
ginning of a third, in a fresh water concrete of 
like nature. This latter dike may have stopped 
in the early stages, as the other two may have 
required all of the dissolved matter that the pore 
could furnish, or it may have dropped beneath the 
surface polished, or have risen above and been- 
cut away in the grinding of the specimen. In any 
event, it has disappeared. It will be observed that 
these dikes meander as did the others, dodging 
the strong aggregate and keeping to the weak- 
matrix. These conditions are probably duplicated 
a few million times in the structure from which 

355 



D 2 



NATHAN C. JOHNSON. 



[CONCRETE! 



this sample was obtained, as it is even now showing outward signs of the inward 
disintegration of which this is a type. 

SUMMARY. 

Summarising this article, it should be noted : — 

i. That concrete structures in which proper care has not been exercised in select- 
ing aggregates, or in mixing raid placing, are honeycombed by millions of pores of 
greater or less size, formed by 
the occlusion of air in the cement 
matrix. 

2. That these pores are 
adapted to promote by capillary 
action the penetration of water 
below the surface layers. 

3. That when w a t e r is 
brought by a capillary pore, aided 
by absorption, or adsorption, or 
both, into contact with a group 
or groups of the unhydrated 
cement particles that exist in al 
concrete, new reactions with 
new volumes are probably set 
up in the rigid matrix of set 
cement. 

4. That these reactions may 
cause disruptive stress to be 




Fig. 14. Disruptive Crystalline Dike, Spillway of Dam, Ithaca, N.Y. 
The Microscope in the Study and Investigation ov Concrete. 



exerted on the cement matrix of the concrete, producing " shear planes " or " slip 
band-, " as evidence of the local failure thus produced. 

5. Thai " shear planes '' and other evidences of local failure by disruption, 
whether resulting from the hydration of cement or from other causes, have their 
origin in a minute pore or fissure. 

6. Thai other disintegrating actions are produced by water entering through pores 
into the mass, by reason of this water, whether fresh or loaded with chemically- 
active salts, dissolving portions of the cement matrix. 

7. That when such entering waters are sufficiently saturated with soluble com- 
pounds, deposition in crystalline form takes place, with tremendous disruptive forces 
exerted on the surrounding material, i.e., the cemenl matrix. 

356 



(&^JNBSiM?^ THE MICROSCOPE IN THE STUDY OF CONCRETE. 

S. That these disruptive forces pressing on the walls of 1 1 1 < * confining pon produce 
one "i more fissures in the matrix, and thai these fissures, in turn, act .is capillary 
passages, with repetition of seepage, crystallisation, and wedging, the crystalline water 
Riling in .is the passages lengthen and widen, until a group of hard, disruptive 
progressing dikes effecl actual disruption. 

i). rii.ti this action is not confined to concretes exposed t<» sea-water, but affects 
other concretes, such as fresh-water dams, filter-beds, buttress walls, sidewalks, etc., 
where defective materials or construction permit the entrance "I water into the 
ma>s. 

10. Thai tli** responsibility lor concrete failures of main- kinds need not necessarily 

rest solely upon the cement, but thai Other factors, such as proper choic< "I aggre- 
gates, efficienl mixing, proper consistency, and care in placing must he held equally 
responsible, since through thes< latter come the inducing causes of failure. 



35 



THE CONCRETE INSTITUTE. 



ICQNCEEXEJ 



T~~ 




■«! ' 



RECENT VIEWS ON 
CONCRETE & REIN- 
FORCED CONCRETE. 



Recent^ Papers & Discussions. 




It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes.— ED. 



THE CONCRETE INSTITUTE. 

THE STABILITY OF QUAY WALLS ON EARTH 

FOUNDATIONS. 

By F. E. WENTWORTH-SHEILDS, M.Inst.C.E., Vice-Pres. C.I. 

The following is an abstract from a Paper read at the Sixty-first Ordinary General 
Meeting of the Concrete Institute. A discussion followed, of which ive also give a short 

report. 
In spite of the large amount of experience which has been gained in the construction of 
quay walls, it is still one of the most difficult problems in engineering to design a wall 
on an earth foundation with confidence that it will be stable when completed. Even if 
the designer of such a wall is assured that it will stand, he cannot with any confidence 
tell you what factor of safety it possesses. The cause of his uncertainty is, of course, 
the difficulty of ascertaining the actual lateral pressure imposed by an earth backing 
and the actual resistance offered by an earth foundation. His difficulties are thus quite 
different from those of the engineer who has to design large masonry dams. The 
latter structures are invariably placed on a foundation of solid rock, and the designer's 
chief care is that the stresses in the masonry of which the dam is composed shall not 
exceed a safe limit. The dock engineer, on the other hand, has to be anxious that his 
wall shall not move as a whole on the comparatively soft material on which such 
structures have in general to be placed. 

The object of this paper is to consider the uncertainties and difficulties which the 
designer of a quay wall has to face, and, if possible, to ascertain how far calculations 
can assist him, and how far he must trust to judgment based on experience. It is also 
intended to urge? upon this Institute the importance of collecting information on this 
subject in the hopes that by degrees these difficulties and uncertainties may be cleared 
away. 

A retaining wall may fail as a whole in two ways : (i) By sliding forward on its base, 
and (2) by overturning. It may be said at once that as regards quay walls, at least, 
the former mode of failure (by sliding forward) is by far the more common. 

Conditions of Stability in a "Gravity " Wall. — The conditions may be sum- 
marised thus : The forces tending to thrust the wall outwards (generally the lateral 
pressure of the earth backing) must be at least equalled by the forces tending to restrain 
it or thrust it inwards. The latter forces are generally the pressure of the water in front 
of it, the resistance; of the earth in front of its toe, and the horizontal resistance to shear 
(or the friction) at the base of the wall. If these horizontal forces balance, the wall 
cannot slide forward. 

The resultant of the outward forces, however, is almost always at a higher level 
than the resultant of the inward forces. Thus a couple is formed tending to overturn the 
wall about its toe. This couple induces a counter-couple tending to keep it upright. 
The forces forming this counter-couple consist, on the one hand, of the weighl of the 
wall acting vertically downwards, together with the weight of any earth or water 

358 



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THE STABILITY OF OUAY WALLS. 



which ma) lir abo\ e I !)<• base "I the wall, and, on I he othei hand, the upward resistance 
of the earth under thai base. 

II the upward resistance >>i the earth beneath the wall is capable "f forming with 
the downward weights a couple al least equal to the overturning couple, the wall cannot 
o\ ei turn. 

In order thai the earth beneath the wall shall he capable ot forming this righting 
couple, two things are necessary. It is obvious that the centre of the earth's resistance 
must he forward of the centre ^\ gravity of the wall and of other loads on the base, and 
generally it is forward also of the mid-point of the base of the wall. Consequently the 
intensity it( upward resistance is generally greatest at the toe and leasl at the heel. To 
pi esen e stability the resistance at the toe musl not he greater than the maximum whi< h 
the earth is capable of offering, and that at the heel musl not he less than the pressure 
induced by the tendency of the earth to rise at this point. 

Thus it will he seen that if the Stability of any given wall is to he ascertained by 
calculation, the following forces must he determined : — 

(1) The amount and position of resultants of horizontal outward forces, such as 
lateral pressure of backing, lateral pressure due to surcharge, pull of ships' moorings 
on bollards. 

(2) The amount and position of resultants of horizontal inward forces, such as 
pressure of water in front of wall, resistance of earth in front of toe, resistance due to 
friction at base of wall. 

Nate. — The forces of paragraph (2) must be at least equal to those of paragraph (1). 

(3) The overturning moment produced by inward and outward forces. 

(4) The amount and position of resultants of vertical downward force-,, such as 
weight of wall, weight of backing resting on wall, weight of water on toe, friction 
between backing and back of wall, friction between toe and earth in front of it. 

(5) Consequent amount and position of resultant of upward vertical forces, such as 
reaction from earth under base. 

Note. — The position of this resultant can be obtained by equating the righting 
moment produced by the vertical forces to the overturning moment due to the horizontal 
forces. 

(6) The consequent maximum and minimum intensities of reacting pressure of 
earth under base at toe and at heel respectively. 

(7) The maximum permissible reacting pressure at toe, and the minimum 
permissible pressure at heel. 

Note.- — The actual pressure at the toe (referred to in paragraph (6) ) must not be 
greater than the permissible pressure (referred to in paragraph (7)), and the actual 
pressure at the heel must not be less than the permissible pressure. 

This method of ascertaining the stability of a wall is illustrated by an actual case in 
Appendix I. The same results can, of course, be obtained by graphic methods. 

The case in question is that of the quay walls of the Empress Dock at Southampton. 

The Empress Dock is a four-sided tidal basin, each side being about 800 ft. long. 
During construction the tide was excluded by means of an enclosing bank. It is made 
of concrete and is 30 ft. wide at base, 45 ft. high from cope to dock bottom, and 51^ ft. 
high from cope to foundation at back. It rests on a moderately firm sandy clay. The 
lower part of the wall is backed by the same clay in its virgin state, as it was built in a 
timbered trench. The upper part is backed with much the same material excavated 
from the dock and cast out and rammed in layers. The angle of repose of the clay was 
about 26 degs. After the backing had been raised to cope level and the ground in front 
of the wall had been removed, the north wall of the dock moved forward. The maxi- 
mum movement was about 23 ft., but the wall maintained its upright position, showing 
that the movement was not due to any overturning effect, or to crushing of the clay 
underneath its toe, but simply to the fact that the resistance of the clay in front of the 
toe, plus the friction at the base, was insufficient to balance the lateral pressure of the 
backing. 

This wall was taken down and rebuilt to the same section, except that the founda- 
tions were carried down to 15 ft. below dock bottom instead of 6^ ft., and the result has 
been quite successful. 

At the same time, in order to try and prevent a similar accident to the other walls, 
large blocks or buttresses were built in front of the toe. These buttresses were each 
20 ft. long, 1 $ ft. wide, and 12 ft. deep, the top of each being level with the dock 

3 59 



THE CONCRETE INSTITUTE. [CONCR ETED 



bottom, and the base 12 ft. below. They were spaced 30 ft. apart in the clear. It was 
thought that the buttresses being 6 ft. deeper than the wall could not plough up the 
ground in front of them, and would therefore resist its lateral movement. This hope was 
vain, however. Another of the walls (the east wall) moved forward, buttresses and all. 

In order to save the west wall after this experience, besides building the buttresses 
in front of the toe, the backing was removed to a depth of about 13 ft. below quay level, 
and by this means serious movement was prevented until the water was admitted to the 
dock. The backing was not restored, the quay being carried on a viaduct. Even under 
these circumstances the quay was constantly showing slight signs of movement, and 
eventually elaborate strengthening works had to be undertaken, which need not be 
described here. 

The conclusions arrived at show that calculations for the stability of quay walls 
cannot in our present state of knowledge be always relied upon, and that failures on the 
one hand, and waste of material on the other, are liable to occur even to the most 
careful and experienced designer. This, how r ever, is not saying that such calculations 
should be ignored. On the contrary, they are most useful in suggesting means for 
increasing in the most economical manner the stability of designs which are known or 
suspected to be weak. 

Devices for Increasing Stability of Quay Walts. — We will now consider some 
devices which have been used for increasing the stability of quay walls and inquire how 
far calculation and experience would lead us to depend upon them. 

(1) Admission of water into dock. — Most quay walls are designed to have a certain 
depth of water in front of them, although in constructing such walls the water is often 
temporarily excluded, so as to cheapen construction. Calculations would indicate that 
the pressure due to this water is a great stabiliser, and experience undoubtedly bears this 
out. A notable instance is the case of the dock wall at Calcutta, described in papers by 
Messrs. Bruce and Apjohn in Vol. exxi. of the Minutes of Proceedings Inst. C.E, The 
wall is 46 ft. high, and founded on a material which was said to resemble putty. In spite 
of the fact that the earth was left in front of the wall for a depth of 26 ft. above founda- 
tion, the wall began to move forward when the backing was raised to within i\ ft. of cope 
level. The movement was arrested, however, by admitting water into the dock to a 
level of 42 ft. above foundation, and no further movement took place, even when 16 ft. 
more earth was dredged out from in front of the wall. Of course, if the earth had all 
been removed before water was admitted, as was done at Southampton, the wall would 
undoubtedly have collapsed. 

It follows that during construction in the dry a certain amount of earth should 
always be left in front of a quay wall until the water is admitted, unless the wall is 
designed to be stable without any water in front of it. 

(2) Sinking foundations deeper. — Calculations would indicate that the forces tend- 
ing to resist sliding forward can be considerably increased by sinking the foundations 
deeper, and experience confirms this conclusion. For instance, as mentioned above, the 
Empress Dock wall which failed was successfully replaced by one of similar design, 
but carried down to 15 ft. below dock bottom instead of 6\ ft. The calculations on the 
deepened wall show that although the outward pressure on the earth backing was in- 
1 reased from 27 tons to 37*6 tons, the resistance of earth in front of toe was increased 
from 2'() tons to 15*4 tons, and the friction at the base from i8"6 tons to 23*4 tons; 
consequently the balance of horizontal forces was as follows : — 

Outward horizontal forces — 

Pressure of backing ... ... ... ... ... 37*6 tons. 

Inward horizontal forces — 

Resistance of earth at toe ... ... 15*4 tons. 

Resistance due to friction at base ... 23 - 4 ,, 

38-8 „ 



Showing an excess of force tending to keep the wall 

stable of ... ... ... ... ... ... ... i*6 ,, 

It is interesting to note that much the same balance on the safe side is obtained if 
Bell's formula- arc used, but the individual forces are greater. 

(3) Building buttress walls in front of main wall. — Let us now consider the device 1 
which was adopted in order to try and prevent movement on the other walls of the 

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/vtS^Vg.K?^] THB STABILITY OF QUAY WALLS. 



Empress Dork, after the north \\ all had failed. Buttresses of i om rete 20 ft. by 15 ft. by 
12 ft. deep were constructed in trenches in front of the- wall toe, at intervals oi 30 ft. 
It was thought, and calculations would seem to suggest, that the resistance to horizontal 
movement would be increased, as the buttresses were 6 ft. deeper than 1 1 1 * - wall. As a 
matter of fact the) seemed to be useless in this respect. Ii is possible that in sinking 
the trenches for these buttresses the clay settled awa) slightly from under the wall, and 
that later water got into the void thus formed, reducing the coefficient of friction there. 
In an) case, when the earth in from of the buttresses was forced forward by the move- 
ment <^( the wall, the buttresses themselves tilted backward and slid up the slope of 
rupture. It is evidenl that this could not have happened if the buttresses had been built 

in under the wall by underpinning, and probably if this had been done they would have 

been effective. In fact, the author has successfully stopped horizontal movement in a 
large retaining wall on clay 1>y underpinning it in this fashion. 

(4) Making wall wider. A wall design which is suspected of being unstable may 
often be improved by increasing its width. This affects its stability in two ways. The 
extra weight of material induces increased friction at the base, and hence increased 
resistance to horizontal movement. And, again, the greater width of base gives a more- 
even distribution of load on that base, and consequently reduces the reacting pressure 
tending to crush the earth under its toe. 

It is of interest to notice that the base width of a high quay wall on an earth 
foundation is invariably much greater in proportion to its height than that of a small 
wall. Many small walls have been built with a base width equal to one-quarter of the 
height. Hut with high walls the widths .are much greater. 

It will be realised that in a gravity wall the chief use of the material of which it is 
composed is to impose weight on the base of the wall, and that the stresses on it are 
very low. Consequently the material itself should be of the cheapest kind. This con- 
sideration has led to the use of hollow monoliths or caissons of masonry concrete or rein- 
forced concrete, which, when sunk, are filled with sand, rubble stone, or weak concrete. 
Some excellent walls of this type have been built at Glasgow, Avonmouth, and elsewhere. 

(5) Removing a portion of the backing. — This is a device which has been frequently 
used to increase the stability of a wall which has been found to move after construction. 
Its effect is somewhat difficult to calculate unless the backing is removed right back to 
the slope of repose passing through the heel of the wall. There are cases where a wall 
has been saved from collapse by its adoption, notably at Southampton, where several of 
the older walls were treated in this way. It has the practical disadvantage that water 
generally finds its way into the void left by the removed backing, and tends to soften 
what is left, and thus to increase the pressure on the wall. 

(6) hnprovi)ig backing. — A far better device is to substitute a light and clean backing 
like ashes for the silts and clays which are so often the only materials readily available 
for this purpose. Ashes, even when charged with water, weigh only about 100 lb. per 
cu. ft., and have an angle of repose of about 35 deg. Had the Empress Dock wall been 
backed with this material, theory would indicate that the horizontal pressure per 
foot-run would have been i6 - o tons, instead of the 27*8 tons estimated for the sandy 
clay. One cannot, of course, verifv such figures by experiment, but the author knows 
of a case of a quay wall, about 56 ft. high, and backed with clay, which started to move. 
The movement was arrested by removing the clay to a depth of about 10 ft. and sub- 
stituting ashes. 

(7) Sloping base of wall. — This device is one over which there has been much dis- 
cussion. From theoretical considerations we would gather that provided the friction or 
resistance to horizontal shear were the same at the base of the wall as it is in the earth 
below, it makes no difference whether the base is sloped or level. In either case, if 
the wall moves it will shear the ground through a horizontal plane passing through the 
lowest point of the wall. But it seems likely that the friction or shear resistance is 
greater in the virgin earth than at the plane of junction between the base of the wall 
and the earth. 

Experience of many walls on the sandy clay at Southampton bears out that a sloping 
base is more stable than a level one. 

(8) Driving piles under base. — This is a device which was frequently adopted at one 
time, though lately it has rather gone out of fashion. The fact is, that bearing piles are 
useful for assisting a weak stratum to bear the weight of a heavy wall, but they are of 

361 



THE CONCRETE INSTITUTE. [CONCRETE] 

little help to resist horizontal movement. Probably in most cases, if well driven, the 
piles take the whole of the weight of the wall. Consequently the friction between the 
wall and the earth beneath it is nil, and the horizontal pressure from the backing is 
largely transmitted to the piles, which may fail by ploughing through the earth in 
which they are driven, and perhaps by breaking under the bending stress thus induced. 
For this reason, and also because they are difficult and expensive to drive inside a wall 
trench, their use has been largely abandoned. Both theory and experience suggest that, 
if used, they should not ue driven plumb, but battered, so that the resultant of the 
horizontal pressure of the backing and of the vertical weight of the wall should be as 
nearly as possible parallel to the length of the piles. 

Probablv if piles are used under a gravity wall, the most effective way of placing 
them is to drive them as sheeting under the toe of the wall. 

Although piles under a high concrete wall are probably of little use, some very 
excellent and economical designs are to be found in America and on the Continent, 
formed almost entirely of piles. In such a wall the horizontal pressure of the earth 
backing is transmitted by means of the front sheeting piles partly to the ground below 
dock bottom and partly to the decking which rests on the piles. The decking thus 
acts as an anchor tie, and is itself prevented from moving forward by the raking piles 
under its tail end. The latter piles should, of course, be driven at such an angle that they 
are more inclined to a vertical line than the resultant of the horizontal pull on the 
decking, and of the vertical weight of the earth above it. Besides thus acting as a tie 
to the sheeting piles, the deck serves to relieve them from the horizontal pressure due to 
the weight of the earth above it, as the latter is transmitted direct to the piles under the 
deck. To give this relief effectually, the deck should be wide enough to cover the slope 
of rupture of the backing, and to nearly reach the slope of repose. The sheeting piles 
must, of course, be strong enough to withstand the bending moment produced by the 
horizontal pressure of the backing. To reduce this pressure as much as possible, a 
specially chosen backing material, such as rubble stone or clean sand, is usually adopted. 

It is probable that the vertical piles behind the sheeting, besides supporting the 
deck, serve to reduce the horizontal pressure of the earth backing, but to what extent 
they do so can only be guessed. 

The author does not know of any case of failure of this class of wall, so that it is 
not possible to compare the results of calculation and experience. 

(9) Anchor ties. — This has been, and is still, a favourite aid to the stability of quay 
walls. In the opinion of many engineers, however, they are of little use, partly because 
they are often placed so far apart that they can only bear a trifling proportion of the 
horizontal thrust, and partly because the weight of the backing which rests on them 
imposes on them a stress which alone is sometimes enough to break them. Probably 
the only case in which they are really effective is that of a jetty with two parallel walls 
back to back with earth between them. In such a case the two walls may be econo- 
mically tied to each other with steel rods. 

(10) Lengthening toe.- — In cases where it is suspected that a w r all will crush the 
material under its toe, the obvious remedy is to lengthen that toe. The White Star 
dock wall has a toe 9 ft. long, which was added in order to reduce the pressure under 
this heavy wall to about 4 tons per square foot. In this case the toe was reinforced 
with old rails in order to prevent its being broken off from the body of the wall. 

As previously mentioned, it is quite difficult to find instances of quay walls which 
have failed by overturning, so that the value of this device can only be conjectured. 

Conclusion. In conclusion it may be said that owing to the difficulty and expense 
of making experiments on large walls, it is the more important that (-.'ireful records 
should be kepi and published of both successes and failures in this class of structure. 
Such records should include not only dimensions of the wall, and careful notes as to the 
nature- of the materials employed, but also the calculations for stability, with the 
formulae used, the assumptions made for the values of constants in those formula', and 
the reasons for such assumptions. 

It is, of course, unlikely that it will ever he possible to design large quay walls 
purely from rules and without some measure of judgment, hut if a body of information, 
as suggested above, could he collected and analysed, it would help to clear away some 
of the uncertainties which now beset that interesting though troublesome problem viz., 
the most economical design of high quay walls on earth foundations. 

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THE STABILITY OI< OUAY WALLS. 



DISCUSSION 



The President, dealing with the difficulties thai encompass an engineer in designing quaj 
W alls foi a modern deep dock, said that, man] yean ago, he saw a <l<»< I* wall being constructed 
.unl predicted its failure bj overturning, which, however, did not occur until some twentj 
years lateT. The original sloping bank behind the wall was simply rilled in withoul being 
punched, the consequence being that undue pressure was brought on the wall. A Great George 
Street engineei was called in, and a new wall built up on cylindrical caissons sufficient to 
defj an earthquake, and al proportionate cost. Failure bj sliding forward occurred in another 
case with a properlj constructed wall through dredging too near the toi «>! the wall. The 
oi the sliding wall at the Empress Dock described by the author wns particularly interesting, 
.md tlu- only remark he had to make upon it was that, apart from going deeper, he should have 
made the base slope backwards so thai the wall would have to lilt before it could slide forward. 
Another explanation of the failure which occurred to him was that the pressure of two to three 
tons at the toe upon the moist earth at the bottom of the dock caused the material to spew up 
in front and so reduce the resistance to sliding. He always used Kankine's formula for 
retaining walls, even for clay, but the main question was, what was the natural slope of clay? 
In his experience, when the clay became moist it acted more like a viscid fluid and it was 
hardly possible to say that it had any real natural slope. When it was dry it was virtually a 
different material altogether. He had always considered the line of rupture as more like a 
semi-parabole with a vertex on the surface, and that would be seen in any section immediately 
after a slip had occurred. In the case of water getting behind the wall, Sir Benjamin Haker 
had showed that the pressure was greater than if the backing were water only. At the 
Victoria Docks, London, anchor ties used between a pair of quay walls exhibited signs of 
incipient failure, and that was found to be caused by the ties rusting through. Fortunately, 
this defect was discovered in time to prevent a disaster. 

Mr. Charles F. Marsh, M.lnst.C.E., did not think there was any real advantage in sloping 
back the foundation of a wall, and particularly in clay, as clay would shear through owing 
to the horizontal pressure behind the wall. A very interesting paper by Mr. Neames in the 
American Society's Journal showed that the pressure was entirely due to the parabolic curve of 
earth failure at the back of the wall. In his own experience he knew of two very well defined 
cases of failure on reservoir walls in London clay. In both cases the walls slid forward; 
there was no sign of any overturning. When a big wall was designed with a clay backing and 
on a clay foundation, undoubtedly the main thing to look after was the sliding forward on 
the base. If much wet weather occurred during the construction of the wall the water got 
behind or round the wall and it sucked in underneath, and it was frequently found that there 
was practically no coefficient friction at all between the wall and the foundation. Recently 
a reservoir had been designed in the London clay, with a tongue underneath 3 ft. wide with 
10 ft. of reinforcement on rolled joists, vertical and horizontal bars. That wall had not yet 
been constructed, but he believed it would be perfectly safe and would not slide forward. 
Personally, he should be perfectly satisfied with a factor of safety of i"i. He was not an 
expert in dock construction, but he thought that dock walls ought to be designed without 
taking any account of the water in front, because it was obvious that the wall must be con- 
structed before they let the water in. 

Mr. Morgan B. Yeatman, M.A., regarded the lateral pressure of earth-work as the most 
vexed question in all engineering design. A good deal depended on whether the wall and the 
foundation under the wall were pervious or impervious. The class of quay walls with which he 
personally had had most to do were walls built of concrete blocks laid under water on a broken 
rock rubble foundation. In that case both the wall and the foundation w-ere to a great extent 
pervious to water, and it was necessary to assume that they had the same level of water behind 
the wall as in front of it ; but it followed from that that they must take the weight of the lower 
part of the wall below the water level as measured in water and not as measured in air. 
With regard to the failure of the wall referred to, the curious thing was that the wall acted 
as if the pressure were behind the centre, and pushed down behind, but, according to all 
theories of calculation, before failure began the pressure on the base was in front of the 
centre. That was why it was hard to understand. He differed from Mr. Marsh, because 
undoubtedly the friction of a flat, smooth bottom wall on the clay was less than the shear 
strength of the clay on itself. The valuable point in the author's paper was that the danger 
in most cases seemed to be more from sliding than from overturning, and the safest way to 
avoid that was to go down deeper into the foundation. 

Dr. J. S. Owens, B.A., M.D., said it seemed to him that most methods of measurement did 
not distinguish between what he might call the adhesion and the friction, that was the force 



THE CONCRETE INSTITUTE. [CONCRETE] 



required to start a body moving and the force required to keep it moving when it had started. 
The crux of the problem was the determination of the constants, the angle of repose of the 
material. It was really impossible to do that, and the sooner they recognised it the better. 
In connection with clay, fine or wet weather and the effect of vibration were variable factors 
which one was liable to forget. It was worth bearing in mind in making a big excavation that 
there might be some larger movements of the earth or clay than the movements in the immediate 
vicinity of the wall, and he suggested that this was a subject pre-eminently for experiment, 
which might be undertaken by the Institute. 

Mr. S. Bylaader (Past Chairman J. I.E.) gave particulars of an ordinary retaining wall 
60 ft. high for which he was responsible, and said that from his experience in designing such 
walls, he had come to the conclusion that, with a relatively low wall, they must add a surface 

load. 

Mr. W. G. Perkins < District Surveyor for Holborn^ remarked that the effect of springs of 
water in the earth would tend to lift the wall in the way suggested by the President, and the 
water would make the clay slippery because it would act as a lubricant. 

Mr. Percy J. Waldram, F.S.I. , was particularly familiar with the failure of walls in 
graving docks due to the lift of the earth in front of the wall, which had not been taken into 
account in the paper. Many such walls were built with an inverted arch for that particular 
reason. He dissented from the statement, frequently put forward by people who ought to know 
better, that widening the base gave more friction. It would certainly seem to be desirable that 
anchor ties should always be imbedded in a small piece of concrete. They must have a trench 
to put them in, and it was far better to fill it up with concrete than to leave the ties exposed to 
the action of the soil. 

Mr. J. Ernest Franck. A.R.I.B.A., recalled his visit to Southampton, when he was struck 
with the enormous size of one of the walls which the Author was constructing there, on which 
occasion he remarked to Mr. Wentworth-Sheilds that when London had disappeared in the 
next 100,000 years, whoever came to make excavations on this site would at any rate find 
something worth digging out. 

MR. WENTWORTH-SHEILDS'S REPLY. 

In replying to the observations of the President and Mr. Yeatman, the Author said there 
were many cases in actual practice where the shear resistance of the material itself below the 
wall was greater than the friction between the wall and the material on which it rested, that 
was to say that the actual plane of the base of the wall where the concrete touched the clay 
was the plane of least resistance, and therefore he contended that it was right to make that an 
uphill plane. There might be something in what Mr. Yeatman had said, that the movement 
of the Empress Dock wall was due to the fact that the earth tended, as it were, to depress 
behind the wall and to rise up in front of it, but he inclined to the opinion that what largely 
accounted for that curious movement was simply that a wedge-shaped piece of earth moved in 
front of the wall, forming a plane of rupture. The wall itself also tended to move up that 
plane, and in doing so it naturally overturned backwards. One wished it were possible to 
ascertain by experiment the actual pressure of different kinds of backing, such as dry gravel, 
gravel charged with water, and so on. If that could be done with any chance of success it 
would be worth the while of the Institute to undertake such experiments. In dealing with clay 
they could only assume some such value for their constants as he had tried to suggest in the 
paper in order to get something that was reasonably likely to be safe and not too outrageously 
extravagant. 

Mr. Perkins inquired whether the direction of the pressure was horizontal or parallel to the 
angle of repose. 

Mr. Wentworth-Sheilds admitted that that was a very difficult question to answer, but when 
considering the stability of a wall against sliding forward he was of opinion that the lateral 
pressure was wholly horizontal. On the other hand, he believed it was right, in considering 
the stability of a wall as regarded overturning, to assume that there was a vertical component 
as well as a horizontal componenl to the lateral pressure : in other words, that the pressure was 
inclined. Although textd>ooks suggested that they should go in for factors of safety of three 
and four, he considered it absolutely hopeless to try with economical design to get, such a 
factor of safety. It could only be done by what might be called unwarranted extravagance in 
wall design, because the quantities Of mate-rial which would have to be- used to get such high 

factors of safety would be- quite unnecessary, and indeed in some cases it was doubtful whether 
>uch a factor could be obtained at all. 



364 



{ a r <TON.VTWl ICTIOvIA I } 



CLECKHEATON GAS WORKS. 



Tin 
and 

umlt 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this headmj reliable information ruill be presented of nevj works in course u/ 
1 Of OOtnpltttd, .md the examples selected will be from all parts of the ivorld. 
It is not the tnten: t these "works in detail, but rather to indicate their eiiste 
and illustrate their primary fra/nrrs. at the most explaining the t ed as a basis 

for the design. — ED. 

CLECKHEATON GAS WORKS. 

Cleckheaton District Council have recentl) erected a n<-w gas works at Moorend, 
various portions of the work, including the foundations to the retort house, an 
irground tar and Liquor tank, a small water tank, and thr<c substructures support- 
i truck weighbridge and two coal hoppers were constructed in reinforced concrete. 
It was decided to have a raft foundation to the retort house in order to reduce 1 1 1 * - 




Timber Sheeting of top of Reinforced Concrete Tar and L 
(to prepare for Concreting. 
Cleckheaton Gas Works. 



Tank. 40 ft. dia. 



pressure on the ground to a maximum of one ton per sq. ft. The siding was constructed 
by tipping 45,000 tons of material to a depth of 32 ft. along the length of the site adjoin- 
ing the L. & Y. R. main line, and the substructures were carried from the solid ground 
to prevent sinking of the weighbridge and coal hopper by subsidence of the tipped 
material. 

The retort house raft is about 85 ft. long by 40 ft. wide, with four longitudinal rows 
of columns at distances of 10 ft., 16 ft., and 10 ft. centres, respectively. The columns 
in the two external rows are at 15 ft. centres, the load on each column being 5 tons, and 
the columns in the two external rows are at 7 ft. 6 in. centres, the load on each column 
being 90 tons. 

The principle on which the raft was designed was reinforced concrete slabs spanning 
between longitudinal reinforced concrete beams under each row of columns. The 
beams and slabs were reinforced with Kahn trussed bars and rib bars. 

305 



NEW WORKS IN CONCRETE. 



1CDNCRET EJ 




Reinforced Concrete Raft for Retort House. 




View showing the forming sides of Reinforced Concrete 
Underground Tar and Liquor Tank. 

Clbckheaton Gas Works. 



366 



' j, l'ON.M LHICT1UNA1.1 
lAKN(,lNll.PlNti — ' 



CLBCKHEATON CAS WORKS. 




Shuttering for Reinforced Concrete Side Structure. 
Cleckheaton Gas Works. 

The liquid residuals of the process of gas manufacture are collected in an 
underground reservoir, which is also constructed in reinforced concrete. The tank is a 
circular one, with an internal diameter of 40 ft., and holds a depth of 12 ft. in. of 
liquid. Its capacity is qq, 000 gallons. The bottom slab and sides of the tank are 
7 in. thick, and the roof, which carries 4 ft. of earth, is composed of a 5-in. slab 
spanning between beams which are carried on the outer wall of the tank and on two 
internal columns. The whole of the reinforcement consisted of Kahn trussed bars and 
rib bars. 

A small underground water tank, 13 ft. 6 in. long by 11 ft. wide and 7 ft. 5 in. 
deep, and divided into two compartments, was also constructed in reinforced concrete. 
The bottom slab and walls of the tank were 6 in. thick, and the roof 5 in. thick. 
Kahn rib bars were used as reinforcement throughout. 

Three substructures to an elevated weighbridge and two coal hoppers are also 
constructed in reinforced concrete. Thev consist of a reinforced concrete platform slab 
which is carried on four external beams supported on four corner columns about 24 ft. 
long, with horizontal braces midway between the bases and the platform for the former, 
and similar columns for the latter. The column bases are in reinforced concrete, and are 
4 ft. square. 

Other plant and buildings erected on the new works are boiler, pump, exhauster, 
washing plant, meter and governor houses, in separate houses, purifiers, condensers, 
and overhead tanks. The works have been laid out on an ornamental scale, and have 
cost ^"42,000. 

The whole of the works, with the exception of the retort house, were designed' 
by Mr. A. L. Jennings, gas engineer and manager, with Messrs. Thomas Xewbigging. 
and Son, of Manchester, as expert advisers. 

367 



NEW WORKS IN CONCRETE. 

it 



Y 




t CDNCBETFJ 



368 



The whole 
of the rein- 
forced concrete 
work here de- 
scribed was de- 
signed on the 
Kahn system of 
reinforced con- 
crete b y the 
Trussed Con- 
crete Steel Co., 
Ltd., of Caxton 
House, West- 
minster, S.W. 

W e a r e 
able to publish 
these particu- 
lars by the 
courtesy of Mr. 
Jennings, who 
also kindly 
placed the 
phot ographic 
illustrations at 
our disposal. 

REINFORCED 
BRIDGES, 
COVENTRY 
LOOP LINE, 
LONDON AND 
NORTH 
WESTERN 
RAILWAY. 

The new loop 
line which has 
just been laid 
on the L. & 
N.W. Railway 
system n e a r 
Coventry, for 
goods traffic, Is 
only about 
three and a 
half miles long, 
but there are 
no less t h a n 
fourteen 
bridges, t h e 
construction of 
w h i c h w a s 
necessary i n 
the formation 
of the track. 
Of this num- 
ber, eight are 
executed i n 
Steel, and one 
in brickwork, 
while the re- 
maining five 



j. CDN> 1 Km IC 1 IUNAI i 
l \ 1 NlilM.I l-MNt. —J 



REINFORCED CONCRETE BRIDGES. 






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[CONCRETE] 




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carry streets or roadways over the rail- 
road, and these are built of reinforced con- 
crete, some details of which are here given. 
In all cases a width of 40 ft. between the 
parapets was allowed, and a similar style 
was adopted both in construction and de- 
sign, with the necessary modifications to 
suit the conditions. 

In three instances the roadway carried 
by the bridge is at right angles to the rail- 
way track, and in consequence these are 
simpler than the remaining two, where 
the arches had to be of the skew type. 
The illustrations in Figs, 2 and 3 show 
the plan and elevation for one of the skew 
arches. The arch has a clear width of 
40 ft. at the springing, the latter being 
situated at a level of about 3 ft. 6 in. above 
the formation level of the track, and 
the soffite is set out as a three-centred 
curve, with a radius of 10 ft. 9 in. at the 
abutments and 30 ft. 7 in. at the crown, a 
minimum of 15 ft. 1 in. being given above 
the rail level, at the crown. The arch ring 
has a thickness of 1 ft. 3 in. at the crown, 
and this increases towards the abutments, 
as the extrados does not follow the same 
curve as the soffite, but is struck from 
one centre only, and this has a greater 
radius than the latter at the crown. A 
section showing the disposition of the re- 
inforcement is given in Fig. 1, and it will 
be seen that Kahn bars were used in both 
soffite and extrados, these being spaced 
w .about 12 in. apart in the straight bridges 
S and about 10 in. in the skew bridges, with 
m diagonals 12 in. or 18 in. long according to 
£ the position. 

" The bars were placed in three lengths, 

z those at the extrados being 20 ft. long in 

<-> the lower part of the arch and 33 ft. long 

S for the central portion, these bars having 

« a lap of 5 ft. The bars in the soffite are 

£ similar, with the exception of those in the 

w central portion, which are only 32 ft. long. 

A minimum cover of 2 in. of concrete is 

given to these main bars. Longitudinal 

rods, I in. diameter, are placed in the 

soffite at intervals of 3 ft. to 5 ft., and these 

are hooked over the main bars at the ends. 

The arch abutment is carried well down 

into the side of the cutting, and has a width 

of 7 ft. with off-sets as shown. The piers, 

on* either side of the arched opening, and 

the wing walls have a batter of 1 in 12, 

and these are formed in concrete, while 

the parapet, which is aboul 6 ft. high, is 

buili of concrete blocks. The whole of the 

designed and executed from 



work was 
drawings prepai 



•e,l l»v Mr. E. F 



370 



r j,lON.MkMK v |'IONAi: 



REINFORCED CONCRETE BRIDGES. 




E 2 



371 



NEW WORKS IN CONCRETE. 



ItQJNCBFTFJ 




Trench, the Chief 
Engineer to the Lon- 
don and North-Wes- 
tern Railway ; and it 
may be considered as 
a good example of the 
economical applica- 
tion of reinforced 
concrete, and a s 
practically no main- 
tenance will be re- 
quired on these 
bridges the adoption 
of the material is 
very wise. 

We are indebted 
to the Chief Engineer 
of the L. cS: N. W. 
Railway, Mr. E. 
F. C. Ire n c h , 
M.Inst.C.E., f o r 
our illustrations. 

REINFORCED 
CONCRETE 
CHURCH, 
HASTINGS, N.Z. 

Our frontispiece 
shows a c h u r c h 
erected in reinforced 
concrete in New Zea- 
land to the designs 
of Mr. F. de J. 
Clere, F.R.I. B.A. 

Reinforced con- 
crete /is particularly 
suitable for buildings 
in New Zealand, as 
the country is sub- 
ject to earthquakes, 
a n d although n o 
serious shocks have 
been experienced for 
many years, such as 
have occurred have 
been known to cause 
serious fractures in 
b r i C k W alls and 
many chimneys ito 
tall. 

\\Y hope later 
on to be able lo pub- 
lish some detailed 
particulars of the 
building lure illus- 
trated. 



372 



j. C'ONM PUC1 lONAl^ 
<i 1 NC.1NH K>1N(. —J 



MEMORANDA 




MEMORANDA. 



t 



Memoranda ana News Items are presented under this hejding, 'with occasional editorial 
comment. Authentic news 'will be welcome. ~ED. 



Reinforced Concrete Sleepers for Tramways.— -Tin- Commonwealth Engineer 
contains an article on reinforced concrete sleepers, from which we give ihe following 
extract : — 

" The Adelaide municipal tramways are regarded as one of the most modern electric 
systems, and under their progressive method it is not unusual to find that as new ideas 
are introduced this system is one of the foremost in testing them. The tramways 
recently inquired into the stability of reinforced concrete sleeper-, and have just com- 
pleted a running test over a period of six months on two of their suburban tracks. 

" These tests have proved that the reinforced concrete sleeper has come to stay, and 
it is claimed that the tracks in which they are usi d are the easiest running. Experiments 
have been carried out to record the amount of oscillation made by carriages running over 
trades in which the reinforced concrete sleeper and the ordinary wooden sleeper are laid, 
and the record thus made shows a vast comparison in favour of the reinforced article. 

" 'Ihe sleepers used are the Joseph Timms reinforced, consisting of a form of 
reinforcement, in conjunction with a metal shoe on which the rail sits. The shoes 
are each connected with reinforcing rods, which are strengthened by intervening 
braces, the whole combining in a truss bridge, which in itself is sufficiently strong, 
but is further strengthened by the addition of the concrete. In the manufacturing the 
ironwork of the sleeper is placed in a mould, into which the concrete is poured, and 
the nec< ssary tamping is done to ensure that every available space is filled. The bottom 
of the mould is made somewhat convex, so that the bottom of the sleeper when it 
issues from the mould has a concave surface. This is regarded as being an improve- 
ment on the usual Hat bottom, as it has a greater tendencv to grip the bed in which it is 
laid. 

" When the sleepers are laid the rails do not come into contact with the concrete, 
and all vibration is taken on the shoe. Thus any possibility of the concrete fretting is 
obviated. The metal shoe grips one side of the foot of the rail in a solid clamp, while 
the opposite rail is clawed by a locking-bar and forced against the foot of the rail by 
two wedges inserted from opposite sides. By this means the gauge may be altered up to 
the thickness of the wedges, but when these are firmly driven in, the rail and sleeper 
become one compact mass, without the possibility of the least movement. At the end of 
the test the track was opened in several places, but in no instance could any movement 
be observed, and in no case was it found necessarv to tighten up any of the wedges used 
in attaching the rails to the sleepers. 

" Particularly in towns should the reinforced concrete sleeper be utilised, as once 
they are laid they are there for years, thus saving the inconvenience which always 
occurs where tracks have to be opened up in thickly populated centres. And in districts 
which are infected with white ants their value is apparent. 

" While the initial cost per sleeper is greater than wood or steel, its advantages 
are so many that its general use would really result in a big saving. It is difficult to 
prophesy exactly how long its life is, because concrete usually improves with age, but 
it is apparent that it is very much longer than that of wood, and once laid is far and 
away cheaper to maintain. Several of the older countries of Europe have realised this, 
and at the present time the authorities controlling the Rome-Naples railway are replacing 
the steel sleepers with the reinforced concrete. 

373 




CDNCEEZEX 



CONSTRUCTIONAL 
E^GINE.ERI'NG - 



jrrrr 



■» 





ttEtOTZSin WIDENING COBHAM BRIDGE. 

Right of picture shows a " Simplex " Piling (22 lbs. section) cofferdam 
being withdrawn (after " founds " of some arches were completed) by 
means of a pole, a set of blocks, and one of our " Grips." Left of picture 
shows .same piling being redriven with a No. 3 McKiernan-T erry Hammer 
suspended from a pole to form another cofferdam— no pile-driving 
frames or complicated plant required. Only sufficient piling for £rd of 
total foundation area ordered ; used three times, then sent on another job. 

ClULD ANYTHING BE SIMPLER? 



Weights of Piling on sale or hire : — 
■' SIMPLEX 22 to 27 lbs. per sq. ft. 

"\' J ' "UNIVERSAL JOIST" from 43 lbs. 




374 



Please mention this Journal ivhen writing. 



j.lTONMUMlTIONAl. 
I \ t.N(.lNhb.WlNti — 



MEMORANDA 



" li mix be argued thai reinforced concrete sleepers become useless if ;i chani 
gauge is contemplated. This maj in certain designs be the case. Bui in the sleepei 
u sed ,ii Adelaide provision is made which enables a changi from a broader to ;i narrower 
gauge, or vice versa, to be undertaken mosl easily, and ;ii a ver) small cost. 

"The highly satisfactory results obtained in South Australia have induced the 
Governmenl oi the State ot New South Wales to undertake exhaustive trial tests on the 

r;iil\\ a\ S. 

New Devon Bridge. The official opening of the new Umberleigh Bridge has just 
taken place. The bridge, which is the onl) one of its kind in the Wesl of England, 
i-> ol strongly built reinforced concrete arches, the walls and abutments being "I mass 
concrete. There are three arches of 50 ft. span of reinforced concrete. The work, which 
cosi about ^2,700, was carried oul by Messrs. Pollard and Co., contractors, <»f Taunton. 
1 1 was supervised by Mr. R. M. Stone, the" county surveyor. 

Reinforced Concrete Picture Houses. Plans have been submitted to the Bristol 
Sanitary Committee for a reinforced concrete picture house a1 Redland. This form of 
construction was not contemplated when the bye-law s were framed, but the Committer 
have decided as a general rule that reinforced concrete shall be allowed subject to the 
details being satisfactory. 

Loans for Public Work. — In view of the uncertainty which has prevailed 
amongst local authorities as to the policy of the Treasury in allowing loans for public 
works, the statement made by Mr. Montagu, the Secretary to the Treasury, in the 
Parliamentary Papers will be welcomed. Mr. Montagu states that at the present time 
loans are only granted by the Public Works Loan Commissioners where it can be 
shown that their purpose is urgently necessary, in the national interests, for the 
furtherance of the War, or is of urgent necessity for reasons of public health. This 
arrangement has been made in pursuance of the Government's general policy of post- 
poning or avoiding all new capital expenditure wherever possible, in view of the para- 
mount necessity of conserving the capital resources of the country in the national 
interests. New loans are therefore only granted in respect of works for which a local 
authority is able to produce evidence of Treasury or Local Government Hoard approval, 
granted since the special restrictions arising out of the needs of the War have been 
effective. In cases where loans have already been granted, but either have not yet been 
advanced or have been only partially advanced, the Public Works Loan Commissioners 
require that all possible efforts must be made by the local authority concerned to post- 
pone or delay expenditure in connection with the loan, and advances are not made out 
of the loan unless it can be shown that these efforts have been made. 

PROPOSED NEW WORKS. 
Canada. — Harbour works are being carried out at Port Arthur and Fort William. 

A breakwater, 20,800 ft. long, is to be constructed at Port Arthur. At Fort William 
the revetment wall is to be extended at a cost of 365,000 dollars. The Department of 
Public Works contemplates in the future the extension of Bare Point breakwater. 

Brierfield. — The Urban District Council propose constructing retaining walls at 
the sewage disposal works at an estimated cost of ^2,500. 

Dunbar. — It has been decided by the Town Council to carry out important repairs 
to the north wall of the new harbour in order to protect the structure from further 
havoc by the force of the sea. 

Motherwell. — In connection with the proposed erection of a coal store for the 
Gas Department, the Corporation have invited an alternative scheme for a brick build- 
ing, with reinforced concrete roof. 

Aberdeen. — The Harbour Board have decided to curtail the extension of the Provost 
Meerns Quay, owing to lack of materials and scarcity of labour. 

Colchester. — Amongst the works for which tenders have been invited during 
the month has been that for the construction of a reinforced concrete tank to hold 
100,000 gallons of water at Severalls Asylum, Colchester, for the Committee of Visitors. 

Reading. — The Town Council have been informed by the Treasury that the 
borrowing of the amount required for the construction of the reinforced concrete bridge 
in De Bohun Road must be deferred for the present. 

Tregaron. — The Rural District Council have decided to erect a small reinforced 
concrete bridge over the river Ystwyth. 

375 



MEMORANDA. 



ICQMCBETEJ 



Brighton. — The Corporation have agreed to make further contributions towards 
the sea defence works between Black Rock and Newhaven. 

Queensland — A high-level reinforced concrete bridge will be built over Moores 
Creek by the North Rockhampton Council, Queensland. 

Dumfries. — In connection with a scheme for the improvement of the navigation 
of the river Nith, Mr. W. A. Tait, Engineer of the Hoard of Agriculture of Scotland, 
recommends the erection of a leaning wall on the Dumfriesshire side. 

Rhondda. — Tenders have been invited by the Urban District Council for the 
erection of a cast-iron or reinforced concrete water tank with a capacity of 30,000 gallons. 

Dundee. — The Town Council have recently invited tenders for reinforced concrete 
floors, etc., at the extension of their electricity generating station. 

Seville. — The Garcia de Madrid publishes a Royal decree authorising the Junta 
de Obras of the Port of Seville to negotiate a loan of ;£ 160,000 for the carrying out of 
improvement works at the mouth of the river Guadalquivir. 

TENDERS ACCEPTED. 

In the past month the War Office have accepted the tender of Messrs. W. Bain and 
Co., Lochrin Iron Works, Coatbridge, for reinforcing columns; and of the Croft 
Granite, Brick and Concrete Co., Ltd., of Croft, near Leicester, for the supplying and 
laying of concrete flags at Larkhill. 

The Kirkcaldy Town Council have accepted the tender of Mr. R. Henderson, Edin- 
burgh, for constructing a concrete toe at the sloping wall in the tidal basin of the 
harbour. 

The Corporation of Birkenhead have provisionally accepted the tender of Mr. J. 
Riley, of Cheltenham, of ^"61,323, for the construction of a portion of the aqueduct in 
connection with the proposed Alwen water supply. 

ERRATUM. 

In our April issue we regret that an error was made in the article on the New Pier 
No. 2, Halifax; page 201, line 20, the depth of the upper girders should read 50 in., 
and not 30 in., and on page 203, line 12, CD. should read C.B. 




THE 



VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum \-\n. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 

The VICTORIA 



is built to last 



WRITE FOR CATALOGUE No. 29. 



THE 



T. L. SMITH Co. 

13, Victoria Street, S.W. 



376 



Please mention this Journal when writing. 




o d 3 



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2 



CONCRETE 



Volume X. No. 8 



London, AUGUST, 1915. 

EDITORIAL NOTES. 



L.C.C. REGULATIONS FOR REINFORCED CONCRETE CONSTRUCTION. 

I in revised regulations for Reinforced Concrete Work wen- submitted and 
approved at a recent meeting of the London County Council, and we would 
refer our readers to the Memorandum on page 42O, winch deals with this 
subject. The revisions that have been made since the second set of regulations 
was prepared are so extensive that they assume great importance to all 
desigfne rs, and we therefore consider it necessary to call attention to the 
principal alterations in these notes. Owing to lack of space, we are unable to 
publish the actual regulations as now approved by the Council in this issue, bui 
hope to print them in the next two numbers, and in the meantime these notes 
of the alterations that have been made will indicate their nature and effect. 
Generally speaking, the regulations have been amended in such a manner as 
to allow greater latitude in the design and construction, and this is no doubt 
due to the efforts of the Institutes which are mentioned in the General Powers 
Act, and who have taken up the subject in earnest with the idea of obtaining 
conditions that are fair. The Concrete Institute has certainly done good work 
in this respect, and although some members of the Institute are averse from 
regulations altogether, we feel that the majority look at the subject in a more 
reasonable manner, and realise that laws are unavoidable, and, indeed, are 
desirable if framed in a proper manner. 

GENERAL. 

Part I. of the regulations, which deals with the general clauses and scope 
of the subject, has been revised in one or two details, but the scope is still 
confined to buildings in which the loads and stresses are transmitted through 
each storey by a skeleton framework of reinforced concrete, with the assistance 
of party-walls onlv, and it has net been extended to apply to reinforced 
concrete which is used for parts of a structure only, although there is no doubt 
that the rules made will be applied in the latter case by District Surveyors, who 
necessaiily require some standard as a basis. The clause relating to floors 
and stairs has been extended, and now includes roofs ; but the inclusion is in 
the form of a statement which permits the use of wood-framing, boarding, and 
battens in the construction of roofs, notwithstanding the fact that all floors, 
stairs, and landings, together with their supports, must be executed with 
incombustible materials. A new clause is added to the effect that no part of 
the reinforcing metal shall be used for conducting electrical currents. 

377 



L.C.C. REGULATIONS. [CONCRETE] 



DATA. 

The data to be used in the calculations is specified in Part II., and the 
dead loads per foot super to be provided for in the different classes of buildings 
have not been varied ; but a new clause has been added, which states that stairs 
and landings shall be calculated to carry safely a dead load of at least 120 
pounds per square foot, but each step shall be capable of safely supporting a 
concentrated load at any point of not less than 300 pounds, and this is rather 
a necessary addition, as no definite data was given in the previous rules. 
Another new clause is introduced, which stipulates that " for calculating the 
resistance moment the angle of dispersion of a point load through hard filling 
and concrete shall not be taken at more than forty-five degrees from the 
vertical." This, we think, would be generally accepted and adopted by 
designers ; but it is as well to get a definite regulation which must be worked 
to. The notes on wind pressure remain unaltered, although the allowances 
made are, no doubt, excessive. A slight variation is made in the wording of 
the definition of " working load," and the finishing materials, such as 
plastering, etc., are now stated to be included, and this has affected the 
following clause, wherein it is specified that for the purposes of calculation the 
average weight of reinforced concrete, together with the finishing materials, 
shall be taken at not less than 144 pounds per cubic foot measured over finished 
surfaces. In the previous regulations the weight to be taken was 150 pounds 
per cubic foot ; but this related to the reinforced concrete only, and the finishing 
materials had to be considered as a separate item. This alteration is 
advantageous, as it simplifies the process of finding the total w r edght to be 
carried, and it certainly does not err on the side of increasing this total load. 

An important revision has been made in the regulation relating to the ratio 
of span to depth of a beam. In the previous rules it merely stated that the 
span should not exceed twenty times the effective depth ; but this has now been 
put on a more satisfactory basis by making the ratio dependent, to a certain 
extent, on the comparison of the actual stress in the material to the permissible 
stress, and it is stated thus : — " The ratio of the span of a beam to its effective 
depth shall not exceed the lesser of the two following ratios — 

tensile stress in regulation at. 

20 X ; 2 ^- 

actual maximum tensile stress 
or 

compressive stress in regulation 42 
actual maximum compressive stress " 

BENDING MOMENTS. 

There is probably no section of the regulations which has been more 
criticised in the past than that dealing with the bending moments to be 
provided lor, and there was very good reason for the criticisms made 1 , as the 
question of continuous beams was ireated in an indifferent manner, and 
endeavours made to lay down rules which did not agree with the laws <l 
mechanics, and thus scientific design was hampered and rendered of no account. 
We are glad to see thai in this respect the Council have mended their ways, and 
there can now be no cause for complaint, inasmuch as they have amended 
clause 35, which deals with the maximum bending moments due to variations 

378 



r^SSSSHSSS L.C.C. REGULATIONS. 

in the incidence of distributed loads over approximatel) equal spans, and, 
l in thei moi e, have introduced a new clause, which states: '" Notwithstanding 
anything in regulation 35, beams may be designed for the exacl positive and 
negative bending moments which will occur al ever) cross-section, whether all 
the spans be loaded, or alternate or any of the spans be unloaded." in this 
lasi clause, therefore, the designer is permitted to design a beam to resist the 
exact bending moment, and surely the regulations would be verj curious ii 
such a condition did not exist, and it rather suggests thai the Council are nol 
quite prepared to substantiate the bending momem formulae as expressed in 
their own regulations. If such is the case, we would suggesl thai they are 
superfluous, and the only rule necessarj is thai quoted above. I he bending 
m< ments for slabs will, of course, be calculated as for beams. We notice thai 

tin' definition of the effective Span has been altered to say that it can be con- 
sidered as the span between the centres of the necessary bearing surfaces, or 
the clear span plus the effective depth of the beam or slab at the supports, 
whichever may be the lesser. Various other minor alterations have been made 

which cannot be mentioned here, but it may be said that it is now stated that 
the reinforcement shall be carried beyond the points of cont rallexure, under 
any condition of loading, by a length at least equal to half the effective depth 
of the beam, whereas previously it was only provided to be taken at least as 
far as the points of contraflexure, but not beyond. 

WORKING STRESSES. 

The tabic of working stresses for concrete has been completely revised, and 
higher values are now permitted, and the increase for richer mixtures has been 
made more in proportion with actual values, and thus this is an improvement. 
It is impossible to state all the values here; but, as an example, the direct com- 
pression stress under the previous regulations for a 1:1:2 mixture was only 
600 pounds per square inch, whereas it is now given at 750 pounds, and it may 
be said that other stresses are dealt with In a similar manner. Various other 
revisions have been made in Part II. which are more or less important, but 
none of them will be of such interest to the designer as those mentioned. 

BEAMS. 

Part III., which deals with beams, has been subjected to alterations, and 
one of the most important of these affects the question of compressive reinforce- 
ment. In the previous regulations the stress on the steel could net be taken 
at more than fifteen times that on the concrete ; but this has been revised, to 
allow the steel to be considered as stressed up to 16,000 pounds per square 
inch if the compressive resistance of the concrete is not taken into account, 
subject to the steel being anchored in accordance with certain conditions. This 
is of great importance, as in the case of shallow beams, where double reinforce- 
ment is necessary, the limitation of the stress en the steel to fifteen timer, 
that on the concrete involves considerable waste of metal, and often proves 
prc-hibitive" in cost. The regulations for shear have undergone changes, and 
a new clause provides that where the vertical shear is taken bv the concrete 
only, the ends of 50 per cent, of the bars of the tensile reinforcement shall be 
inclined across the neutral plane of the beam, and shall be carried through a 
depth equal to the arm of the resistance moment, or the whole of the bars shall 
be carried through to the ends of the beam. 

B 379 



L.C.C. REGULATIONS. [CONCRETE] 

SLABS. 

The clause relating- to distribution bars has been amplified, and the regula- 
tion dealing with the width of slab that can be calculated as acting as the flange 
of a tee beam has been amended. In the latter case the width has been 
increased to the distance between the centres of the ribs of the tee beams, or 
twelve times the thickness of the slab, provided such width does not exceed 
a fourth of the effective span of the tee beam. In addition, a clause has been 
added which deals with L-beams. Various other amendments have been made, 
and nmongst these is the alteration of the regulation limiting the effective depth 
of slabs, which was originally stated to be not less than 4 in., and is now given 
as 3 in. 

PILLARS. 

Pillars are dealt with in Part IV. of the regulations, and here, again, many 
alterations have been made. One, the first that is met with, is that relating 
to the joints in the vertical reinforcement. As now stated, the clause provides 
that there shall be an overlap at least equal to twenty-four times the diameter 
of the upper bar, and this is far more reasonable than the original stipulations. 
It may be said that some parts of this section have been revised to such an 
extent that they are no longer recognisable, and although, in some cases, the 
revision is a question of form only, in others the revisions materially affect the 
design, and, generally speaking, the regulations as now put forward certainly 
allow the designer more latitude, and are therefore welcome, there being no 
necessity to have rules which do not allow of the designer's skill being utilised. 
For details of the actual alterations that have been made we would commend 
our readers to the two sets of regulations, as space will not permit us to go 
into them fully. 

WALLS. 

The chief alteration in this section applies to the requirements for hollow 
blocks, and these are given more in detail, and allow thinner sides to be used 
than formerly. 

The sections dealing with foundations and protection have undergone no 
change, and in materials and testing the chief alteration is that dealing with 
the question of deflection, this having been put on a more satisfactory basis. 
Some small alterations have been made in the section devoted to Workmanship, 
these relating to concrete, or mortar, which has been frozen, which is now 
prohibited from use, and to the fixing of wood in concrete for fixing purposes. 

CONCLUSION. 

Generally speaking, the regulations as now revised appear to be reasonable 
and efficient, and it is to be hoped that the consent of the Local Government 
Board will be obtained, and the rules brought into force as quickly as possible, 
and should any modifications be found necessary at a future date, when experi- 
ence has been obtained by their application, there should be no difficulty in 
making them, after proper consideration has been given by all interested 
parties. 

We have only one stricture again to put on record — namely, in respect 
of the extraordinary delay in arriving at the present draft. The Act was passed 
in [909 authorising the issue of these regulations. We are in [915, and six 
lull years have elapsed where one should have sufficed to arrive al an under- 
standing. The progress of reinforced concrete has been materiall) hindered 
in the meantime. 

380 



I - .. CON.Ml'UCHUNAl.) 
[t\ hMC.lM.l.KlNti —J 



PORT DUNDAS DISTILLERY. 







PORT DUNDAS DISTILLERY. 

By ALBERT LAKEMAN, M.S.A 



The building here described is particularly interesting as jn example of the application of 
reinforced concrete construction to factory buildings. ED. 











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The importanl buildings erected at Port Dundas for The Distillers Co., Ltd., 
from the designs prepared by Messrs. F. Burnet and Boston, architects, of 
Glasgow, contain many interesting features, and reinforced concrete has been 
employed for the constructional material throughout. When designed in an 
efficient and economical manner, as is the case in these structures, rein- 
forced concrete is cheaper as regards initial outlay, and it has the further 
advantage of being peculiarly adaptable for 
structures of this type, which essentially have a 
character quite distinct from the ordinary factory 
or warehouse type, while fire-resistance, good 
lasting qualities, and homogeneous construction 
are of primary importance. 

The main new building- is the Malt House, 
which adjoins Harvey Street, this having a length 
of about 240 ft. and a width of 57 ft. The portion 
adjoining Yulean Street is the Draff Store, and 
this has a length of about 90 ft. and a width of 
55 ft. An existing silo building occurs at the 
end of the Malt House remote from the Draff 
Store, and the kilns adjoin the new building also 
at the Lmd on the side remote from Harvey Street. 

Ihere are four floors, which give a total 
height of about 63 ft., the lowest of these occur- 
ring partly below the ground level in Harvey 
Street, and being utilised for the drums and 
having air passages 3 ft. 6 in. deep under the 
floor arranged to leave passage for bands under the two rows of drums. 
The first floor is the "steep" floor, each steep of which gives a load of 
30 tons to be carried in addition to the calculated superimposed load of 1 cwt. 
per ft. super for the remainder of the floor area. Above the steep floor the 
hoppers aie constructed, these being about 18 ft. high and 13 ft. 6 in. square. 
They are arranged in rows across the width of the building, and the total 
weight of grain in each hopper when full is 66J tons. The floor over the 




Fij*. 1. Foundation Details. 
Port Dundas Distillery. 



B 2 



381 



ALBERT LAKEMAS. 



ICQNCBETFJ 



hopper is 9 ft. high, and it is calculated to carry a superimposed load of 1 cwt. 
per ft. super. It will be seen from this section and particulars that consider- 
able loads had to be carried, and the type of building- is not a common one. 

The Draff Store is a simple building - , consisting- of ground, first and second 
floors, with steel roof trusses over the latter, and with floor construction 
designed to carry 2 cwts. per foot super in addition to the dead load. With 
the exception of the steel roof trusses above mentioned, the whole of the work 
in the new buildings has been executed in reinforced concrete on the Considere 




Fifj. 2. Work during Construction. 
Port Dundas Distillery. 

system from designs and details prepared by the Considere Construction Co., 
of 5, Victoria Street, Westminster. 

There are four main longitudinal rows of interior columns in the principal 
new building at the lowest floor level, and these are spaced at 14 ft. 
1 in. centres in the longitudinal direction, with a foundation slab carried down 
4 ft. below the level of the bottom of the air passages mentioned previously. 
The columns generally at the lowest level are 14 in. octag< nal, with eight lines 
of vertical reinforcement, and a typical foundation detail is illustrated in Fig. 1, 
this being 7 ft. 6 in. square; with a minimum thickness of <s in. at the outer 
edges, increased to 4 ft. at the point of intersection with the column. 'The 
reinforcemenl consists of a lattice of |-in. diameter bars on the under surface 
and four continuous stirrups passing round these bars and carried well up 

382 



[■ j. IT&NJIUlHTICMAl! 
1A KM(,lNhb.WlNt. — , 



PORT DUNDAS DISTILLERY 




Fig. 3. Building in course of construction. 
Port Dundas Distillery. 




Fig. 4. Port Dundas Dis 



STILLERY. 



383 



ALBERT LAKEMAN. 



IOGNCBETEJ 



di'LlVla, 



.'A'd.Z'l 



into the mass of concrete above, thus anchoring- the tensional reinforcement 
and providing" for resistance to shear. In order to enhance the natural strength 
of the concrete and thus allow the compressive stress to be raised to an economi- 
cal fWure, the vertical reinforcement in the column is encircled with the con- 
tinuous spiral, in accordance with the Considere system, and the main rods 
and the spiral are carried well down into the column base. In the case of 
the columns in the row next the external wall adjoining- Harvey Street, the 
foundation was constructed in conjunction with, that under the wall piers 
— the latter being- of 
reinforced concrete 16 
in. square, and having 
six lines of vertical 
reinforcement — as the 
two supporting- mem- 
bers are only about 
7 ft. 6 in. apart. This 
foundation is 12 ft. 
by 8 ft., and it is 
reinforced to act as 
a beam between the 
two columns, with 
the side portions as 
cantilevers from either 
side of this beam, 
thus ensuring- a rig-id 
foundation capable of 
distributing- the load 
uniformly over the 
soil. The small 

c o 1 u m a s supporting" 
the floor over the 
central air passag-e 
are probably some of 
the smallest reinforced 
columns in existence, 
as they have a total 
length from the floor 
level to the underside 
(jf the foundation 
of 4 ft., and they are 

5 in. square with four vertical bars, and a base only 12 in. square. The floor 
over this air passage was constructed in this manner without cross-beams, 
but with one central longitudinal beam carried by these small columns, in order 
that the resistance to the flow of air should be reduced to a minimum. 

Owing lo the drum floor coming' partly below the level ol Harvey Street, 
ii was necessary to construct retaining- walls for a varying height, according to 
the fall of the street, the maximum being about 17 ft. As the external walls 

are of reinforced concrete, with weight-carrying piers at 14 ft. 1 in. centres— 

3X4 




Fig. 5. Beam details to Steep Floors. 
Port Dundas Distillery. 



fj T noNM'kMRTlONAl.'i 
( A KMilNhl-'.KlNCi —J 



PORT DUNDAS DISTILLERY. 




,2 > 






that is, in line with the internal columns 
the portions below the ground are 
designed to act as vertical slabs, which 
lining the pressure on to intermediate 
li rizontal beams, and the latter, in turn, 
transmit the pressure to the main piers; 
thus the method is similar to that 
adopted in floor construction when slabs, 
secondary beams, and main beams are 

used. The horizontal beams are 
generally 17 in. by 6 in., and spaced al 
distances apart varying from 3 ft. 6 in. 
to 6 ft. 6 in., while the slabs are 5 in. 
thick, and reinforced with vertical and 
horizontal bars in the inner surface. 

The (lesion and lay-out of the beams 
and slabs forming the steep floor is 
obviously governed to a great extent by 
the size and disposition of the sleeps, 
which are placed in two longitudinal 
rows. The columns from the floor below 
are continued up through this floor, and 
main beams, having- a span of 14 ft., are 
employed, with secondary beams at about 
7 ft. centres. 

The slabs generally are 4 in. thick, 
with |-in. diameter bars at 5-in. centres 
and distribution bars at right angles to 
the main reinforcement, spaced at 12 in. 
centres. The secondary beams are 8 in. 
wide and 18 in. deep, including the slab, 
with two bars as tensional reinforce- 
ment in the lower surface and three 
continuity bars in the upper surface 
where passing over main beams and 
columns. The main beams are 9 in. 
wide and 21 in. deep, with four bars in 
the lower surface at the centre and three 
continuity bars in the upper surface 
where passing over the columns. Where 
the steeps occur it was necessary to 
leave a circular opening in the floor about 
11 ft. 3 in. in diameter, and this was 
formed by beams 12 in. deep, which cut 
off the angles between the main and 
secondary beams, thus giving an oc- 
tagonal trimming, that was brought to 



38 



ALBERT LAKE MAN. 



[CONCRETE] 



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386 



r J.HON5TUIKTIONA1J 
L<vtJM(JNKKWIN(. — , 



PORT DUNDAS DISTILLERY. 




Fig. 9. Interior View»of New Building. 
Pour Dundas Distillery. 





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Fi^. 10. Square Panel over Hopper Floors. 
Port Dundas Distillery. 



3*7 



ALBERT LAKEMAN. 



C2S2EIS 



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the finished shape by 
providing" additional 
concrete to the beams, 
which made them 
curved on the side next 
the opening, as shown 
on the detail in Fig. 5. 
The octagonal columns 
are carried up to the 
level of the hopper floor 
without reduction in 
size, but above this 
point thev are reduced 
to 9 in. square, with 
four vertical bars, and 
some are stopped en- 
tirely. Those that are 
continued through the 
hopper floor are again 
reduced to 8 in. square 
at the top floor level, and 
a similar size is employed 
for those columns which 
occur in this top floor 
only. A detail of the 
hopper walls is shown in 
Fig. 8, this being 13 ft. 

6 in. long, with a mini- 
mum thickness of 5 in. 
for the central 8 ft. of 
length, a n d being 
splayed at each end to 
give a maximum thick- 
ness of 9 in. at the point 
of intersection with the 
adjoining w alls. The 
transverse walls are of a 
similar type, but have a 
minimum thickness of 

7 in. and a maximum of 
9 in. A detail of the 
c o n s t r u cti o n at the 
bottom of the hoppers is 



shown in Fie*. 1 



jj 



the 



sloping concrete having 

a thickness of 5 in. lead- 
ing down 1o the mouth 



38S 



r i»„ 00N>T1HJCT10NAL2 



PO/^T DUNDAS DISTILLERY. 



of tin- hopper, which is 6 in. square. A wrought iron ring, [j in. diameter, 
is pi. iced round the opening, and the main reinforcing rods are passed round 
t his. The genera] arrangement <>l the beams around the sloping portion, 
an( j the disposition of the bars, is -noun in the details. The plan of the floor 
panel shows the arrangement ol the reinforcement in the floor over the hoppers, 
and a typical beam detail is illustrated in Figs. 7 and 10, this being 14 in. deep 

and (> in. wide, will) the bars 

arranged as shown on the 
drawing. 

The roof over the malt- 
house is arranged with lour 
rows of beams, placed longi- 
tudinally, these being t6 in. by 
in., ami having a span of 
14 ft., and no transverse 
beams, but 4-in. slabs are pro- 
vided, with additional reinforce- 
ment transversely between the 
columns, to cut the longitudinal 
slabs up into panels about 11 ft. 
by 14 ft. These slabs are con- 
structed with a slope from the 
centre to the side walls, giving 
a fall of 12 in. to the roof, and 
to allow this the longitudinal 
beams are at different levels, as 
required. The side walls are 
formed with parapets 3 ft. 
high above the roof, and these 
parapets, and the wall below, 
are in reinforced concrete 5 in. 
thick, with horizontal and 
vertical bars in both surfaces. 

The draff store is con- 
structed with three longitudinal 
rows of interior columns ar- 
ranged to divide the floors up 
into panels about 13 ft. square, 
and these columns are 1 1 in. square on the ground floor, reducing to 9 in. on the 
first floor and 8 in. en the second floor. The type of foundation employed is 
different to that used in the malt-house, consisting, in this instance, of a square 
block of reinforced concrete, with a length of side of 4 ft. or 5 ft., according 
to the load, and a uniform thickness of 18 in. or 2 ft. The reinforcement 
consists of bars in both upper and lower surface, and in both directions, and 
continuous stirrups are provided to connect both sets of bars and resist the 
shear. The floor slabs to the first and second floors are 5 in. thick, carried by 




Fig. L2. Kiln Roofs. 
Port Dundas Distillery. 



389 



ALBERT LAKEMAN. 



ICONCEEXFJ 




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39 ^ 



r^CONMVUCTKaNlAll 
1/ V t-T4('INH.WINti — J 



PORT DUNDAS DISTILLERY. 



beams 20 in, deep and 6 in. wide, which are supported directlj bj the columns. 
These beams are reinforced with four bars in the lower surface :ii the centre 
of the span, and two of these only are continued through to the ends, while 
three bars are provided over the columns in the upper surface to give continuity. 

I In' roof is formed with 4-in. slabs laid to a slope, and carried by beams 
1 } in. deep and 5 in. wide. A chamber, 1 -' ft. high above the roof, is con- 
structed next the malt-house, with reinforced concrete walls 5 in. thick, while 
the external walls of the draft store generally are built of brickwork. 

Various other work was executed in reinforced concrete in addition to 1 1n 
malt-house and draff store, as, for example, the beams, columns, and hoppers in 
the grist house, this structure being about Sj ft. by 57 ft. 6 in. In this building 




■ ■ ■ n 



■ ■ ■ 








Fij*. 14. Gene:al View of New Building. 
Port Dundas Distillery. 

there are seme 17-in. octagonal columns, which carry a load of about 260 tens, 
and these are reinforced with twelve vertical bars, and have a foundation slab 
8 ft. 6 in. square. There are also sixteen small hoppers about 8 ft. square, 
and three large hoppers about 17 ft. square, all constructed in reinforced 
concrete, in addition to the fleer construction at the first floor level. 

The new buildings necessitated certain alteration to the kilns and the 
formation of a new roof, and this was carried out in reinforced concrete. There 
are four rcofs, each covering a space about 45 ft. square, and these are sloped 
up with a rise of about 19 ft., with a central shaft 6 ft. 3 in. square at the 
apex, about 25 ft. high. The roof is formed with sloping beams and hips, with 
4-in. slabs between, and the vertical shafts have 4-in. reinforced concrete 
sides. Fig. 11 shows a detail of the sloping roof beams, which are 6 in. wide, 
and the method of tying the beams at the top will be seen, while the detail 



391 






ALBERT LAKEMAN. IC2NCRETEJ 

in Fig. iia illustrates the reinforced concrete to the sides and top of the vertical 
shafts mentioned above. A photographic view of these kiln roofs is given in 
Fig. 12. 

There are many interesting - features in the new work which it is impossible 
to describe here ; but it may be said that the whole scheme is an excel- 
lent example of scientific design and construction, and it is a worthy addition 
to the works in reinforced concrete. 

The contractors for the work were Messrs. Melville, Dundas, and 
Whitson, of Glasgow. 



VJ2 



v oorwuucrioNAi; 



PROBLEMS IN THE THEORY OF CONSTRUCTION, 




PROBLEMS IN THE THEORY 
OF CONSTRUCTION. 

INFLUENCE LINES FOR BEAM 
DEFLECTIONS. 



=^. 



By EWART S. ANDREWS, B.Sc.Eng., M.C.I. 

The following article will be of interest to engineers and others -who have to deal ninth these 

questions. — ED. 



THE use of the influence-line method of dealing with problems in structural 
design is very useful in finding the deflections in simply-supported beams due 
to an irregular system of loading- The influence line for the deflection at any 
point, say P, Fig. 1, of a beam will be a line such that its ordinate at some other 
point O will give the deflection 8 PQ at P due to a unit load placed at O : it is a 
picture of the way in which the deflection at P varies when the unit load moves 
from one point to another on the beam. 




fli 



A " 



fit- 



ccL 



y 



Fig. 1. 



I 

Fig. 



Maxwell's Law of Reciprocal Deflections. — We will next prove the 
abova important law, which states that " The deflection at P for a unit load 
ac i'lg at any otlier point Q on a simply-supported beam is equal to the deflec- 
tion at Q for a unit load acting at P." 

To prove this law we will take a simply- supported beam AB, Fig. 2, of span 
/, and consider the expression for the deflection at P due to a load \V at O. 
This can be shown to be equal to : — 



6El\ 



(1-a) x * -a (1-a) (2 -a) f X 



i.e., 



w 



= (1-a) a \x--a(2~a) f J- 



(1) 



(2) 



If the load were at P, and we put fi for « and y for x in the above equation, 
we shall get the deflection at Q given by :— 

6EIS Q _ 

" ( 



W 



(l-P)y\y 2 -p(2-p)l 2 \ 



(3) 



*See, for instance, the Author's " Theory and Design of Structures," p. 218, equation 10. 

393 



EWART S. ANDREWS. 



CTCEETFJ 



We have now to prove that the results of equations (2) and (3) are the same. 
To prove this we note that x = l—pl=l (1— P) and fil = l — x ; also 

y = l-al = l (1-a) 

.'. (l-»,=^,Z(l-a)=*(l-a) (0 

/ = / 2 (l-«) 2 = / ? (l-2a + a 2 ) (5) 

We have shown above that pl = (l — x) ; further 

(2-jS)/=(l + l-iS)Z=/ + (l-jS) /=(/+*) 

.". P(2-P)l 2 = (l-x) (l + x)=l 2 -x 2 (6) 

Putting lesults (4), (5) and (6) into our equation (3) we get 

6R1 **--' x (l-a) \ f ( 1 - 2a + a-') - (f- - x 1 ) j 



w 



= x(l-°)\x 2 -(2a-a*)?\ 

= x(l-a) { ( X 1 -a(2-a)f } - 



(7) 

This is exactly the same as the result of equation (2), so that we have &p = &q, 
thus proving the law. 

Taking W=l, we may write equation (2) as 

EI ^p^^-^Ix- -a (2-a)?l (8) 



Then the curve drawn for this e iiiation for any given value of x, cr for various 
values of a, gives us an influence line for the deflection at the given point, from 
which the deflection due to a complicated system of loading may be readily 
obtained in the manner next to be described. 

Case of Deflection at the Centre. — In most cases that arise in practice 
the deflection at the centre is of greater importance than at any other point. 

. ' . Putting x=~ we have 



E/8, 



= -(l -a) ' 1 -a(2-a) > 

12 '.4 > 

> (!-«) ( /, v -.11 



(9) 



[We have divided through by — 1 to get rid of the minus sign which arises in 
the formula and merely indicates that the deflection is downward.] 

This formula gives the following coefficients from which the influence line 
can be drawn, as shown in Fig. 3. 



Values of «- 


Deflection Coefficient 


■:>() 


•ojos 


•55 


0205 


•60 


0197 


■65 


'0183 


•70 


0165 


•75 


'0143 



Values of a 



SO 

•85 

•90 

'95 

1 00 



Deflection Coefficient 



01 18 
OCM 
006 ! 
•0031 




394 



j fONMLMK TIONAl 
c. i m,im LRINO — 



PROBLEMS IN Till-: THEORY OF CONSTRUCTION. 



Since a/ must be greater than x in I^ig. 1, we only tabulate as shown ; for 
lowei values we work from the othei end and, from consideration ol symmi 

the Curve will he the same on each side 







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Fig. 3. Deflection Influence Line for Centre ok Span. 

Plotting these results upon a unit span we get the influence line shown in 
Fig. 3 ; to find the deflection at the centre of a beam, due to any given loading, 
we then place the given loading on the unit span and multiply each load by the 
ordinate of the curve. The results are then added together, and if this final sum 
is z, we have the deflection S c at the centre given by the relation. 



I 



i.e., 



8 = 



zf 
EI 



(10) 



This process will probably be more easily followed by the aid of the following 
numerical example. 

Numerical Example. — A girder whose moment of inertia is 9,000 in. 4 
carries the load system shown in Fig. 4, the span being 40 ft. Find the 
deflection at the centre of the span when the load is in the position shown, 
E being taken as 1 3,000 tons per sq. in. 

We first place this loading in its proportionate position upon the unit span 
of Fig. 3, and then draw ordinates to the influence line, as shown in dotted lines; 
then, multiplying each ordinate by its load 
and adding, we get 

20 X '0091= T82 

20X'0180= '360 

20 x "0207= '414 

8X'0154= T23 

Total =*=1"079 




39: 



EWART S. ANDREWS. 



[CQNCBEX FJ 



. g __ 2/ 3 _ r079x40x40x40x 12X12X12 
c EI 13,000X9,000 

= 1'02 ins. 



Deflections at Quarter Span. — If the deflections are required at some other 
point, say at quarter span, we put the given value of x in equation (8) ; thus 

obtaining in the case in which x =- 

4 

EI.S P = ( -^± l \l~a( 2 -a)A 

24 46 > 



Reversing the sign as before, this comes to 

^ = (L^ a ( 2 -„)-lJ- 



r 



24 < 



(11) 



This formula can be used only for values of a greater than - ; for points 

corresponding to smaller values of a we must work from the other end, putting 

3/ 
x = — and (1— a) for a, thus getting 

4 

cwS 3 a/( 9/ 2 , 2 x 2 ) 

El0p = * — — v l —a) I i 

24 < 16 > 



or 



EIS 



P=^ {l -^)-l 



16 



<M 7 2 ) 

— — - a L r 

846 > 



(12) 



'005 









•0/5 



S|oan Ratios. 
•3 * -5 *e *7 



\ 






































/ 


\ 






































/ 


s 


v 








































\ 








































\ 














































































































/ 






































/ 


/ 






































/ 




































































































s. 








































\ 














/' 









































































































































■8 



/•o 



0O5 



o/o. 



OI5. 



Fig. 5. Deflei now Influence Line for Quarteb Span. 



39 6 



r.cr^.sTkMK-noNAi.1 ]>RO!UJ<MS IN Till'. THEORY OF CONSTRUCTION. 
These Formulae give the following results: — 



Valium i 


I Reflection ( 'oHin ienl 


\ alue of a 


I Reflection ('< effii ienl 








■55 


01 




•oo • 


60 


0130 


10 


•oo 


7.5 


0119 


15 


0077S 


70 


0106 


10 


•00' 


•75 


00911 




01 17 


•80 


•00750 


■ JO 


0130 


'85 


0)572 


35 


•0139 


'90 


00 


'40 


0144 


"95 


00195 


•45 


'0145 


100 





'50 


T143 







Fig. 5 shows the resulting influence line for deflections at one-quarter span, 
and is used in any particular case in exactly the same manner as described for 
the deflections at the centre. 

In the case in which the load is uniformly distributed over the whole or part 
of the span, we proceed in the manner common to influence lines by finding the 
area of the influence-line diagram below the load and multiply by the intensity of 
the load ; this result is used for the value of z in equation (10). 



397 



NATHAN C. JOHNSON. 



ICDNCRFXfi 





MICROSCOPE AS AN AID IN 

PROPORTIONING CONCRETE 

FOR STRENGTH. 



Demonstrating the Influence on Strength of the Ratio of Cement 

to Aggregate " Burden/* 
By NATHAN C. JOHNSON, 

Consulting Engineer, New York City. 

Third article of series. — In reprinting these articles ive "would state that the opinions 
expressed are those of the author, and the Journal as such does noi necessarily associate 
itself 'with the conclusions arrived at. The articles are reprinted by the courtesy of the 
"Engineering Record, " U.S.A., and the illustrations ha've been placed at our disposal by 
the author. — ED. 

In the preceding articles of this series there have been discussed certain defects in 
commercial concretes, together with some weaknesses, primary and secondary, directly 
attributable to them. In adducing proofs for these discussions the microscope, in con- 
junction with the photographic camera, has been the principal reliance. The same 
means will be employed in the investigations in this present paper, but the manner of 
their utilisation and the character of the problems attacked will be somewhat different. 

MICROSCOPE A HANDY TOOL, 

In order that these variations of procedure may be understood, it may be well to 
emphasise here that the microscope is not so much a delicate, scientific instrument as 
it is a very handy tool that does not necessarily require a prolonged training for its use. 
There is no mystery or complication about a field glass. That is an everyday affair, 
used to magnify a distant object until it becomes sensible to our limited range of vision. 
Nor is there any mystery about the ordinary magnifying glass, which shows an 
enlarged image of a small objeel near at hand. Yet, if an arrangement of lenses similar 
to this field glass or this magnifying glass is so mounted as to be mechanically con- 
venient, it is invested with the dignity that goes with the name of "microscope"; 
and, inferential!}', its use is prohibited by any save grey-haired scientists. On the 
contrary, the microscope is a most convenient tool, adapted to a wide range of uses. 
Nor is it necessarily complex, or delicate, or costly. Even an inexpensive instrument 
can give very excellenl results, and will open the door to a field undreamed of by those 
who know matter only in the gross. 

Micro-photography is merely the using of photography to render permanent the 
otherwise transient images seen through the microscope. Essentially, it is nothing more 
than a ( ana ra-bellows lit ted to the eye end of the microscope ; and its employment should 
be no more complex than the iis<- of a hand camera. If the photo-micrographs used to 
illustrate these discussions are considered as ordinary pictures taken by a magnifying 
lens in an ordinary camera, it may aid in an understanding and a proper- valuation oi 
'hem. In cement investigations this conception is nearer the truth than may he 
imagined, for it is often of the greatest service to lake direct photographs of the 
concretes at from one-half to four powers, without the interposition of a microscope. 
By this pro< edure the ( hara< ter of gross sections and the interrelation of large aggregate 
may be studied, while, by supplementing these photographs with others taken at higher 

398 



1 iSFgiBWiaroq THE MICROSCOPE IN rill- STUDY of co.YCflZiTE. 




NATHAN C. JOHNSON. [CONCRETE 



powers through the microscope, the entire range from gross to micro-structure is covered, 
so that true values are established by comparison and erroneous conclusions prevented. 
This procedure will be followed in obtaining evidence for the discussions of this paper. 

Having been chiefly concerned in previous articles with certain defects of concr :te, 
and having learned of some of the consequent ills that concrete is heir to, it becomes 
of prime importance to inquire as to how those defects may be either remedied or 
wholly eliminated, so that future construction may be more reliable. 

In all probability, those concretes which have so far been examined — all of them 
commercial or field-mixed concretes, as distinguished from laboratory-mixed concretes 
—had proportions of cement, sand and stone such as 1:2:4, 1 '■ 2 l '■ S-> l : 3 : 6 or 
1:4:8, since these are " standard " in field work. Yet, although proportioned and 
mixed in accordance with accepted practice, the concretes seem to be decidedly faulty. 

It would be most interesting to know why this is so. There certainly is no denying 
the fact. Should the cement be blamed? That, at least, is current practice. Were 1 
the proportions wrong? Was there loam in the sand — whatever of good or evil that 
may reallv mean? Was the mixer in poor condition? Speculation is easy, but 
unfruitful of results, unless it should lead to an inquiry as to what the " old reliable," 
" practical " 1:2:4 or 1:3:6 or any of these arbitrary mixes really are. It is a 
heretical question, but as it is one of prime importance it may be well to answer it by 
running' the gamut of these proportions in laboratory mixes, testing" them in the usual 
ways, then sectioning and polishing both large and small specimens to determine the 
internal behaviour and arrangements by means of the photographic camera and the 
microscope. 

PHOTO-MICROGRAPHS OF DIFFERENT MIXES. 

In the top row of Fig. 15 are shown one-fourth-power photographs (taken by direct 
photographv) of five laboratory test cylinders, each 8 in. in diameter bv 16 in. long, 
all made with the same aggregate. Four of these are stereotyped mixes, proportioned 
1:2:4, 1:2:5, 1:3:6 and 1:4:8. The fifth is an unrecognised friend, so far as 
most field work is concerned — a concrete made with the same aggregate as was used 
in the others, but graded to conform to Fuller's curve of maximum density. (Wm. B. 
Fuller in " Concrete, Plain and Reinforced," by Taylor and Thompson, p. 183.) Its 
proportions are 1 : 1*41 : 4*34. 

Obviously the photographs in the top row have been touched up. 1 he actual 
photographs of the sections were rather small. These were enlarged 1^ times full 
size, to a diameter of 12 in. To bring out the various features, red and black drawing 
inks were resorted to the black to bring out the stones and outline the boundaries 
of those dislodged in grinding, and the red to make prominent voids and cracks. 
These retouched enlargements were then re-photographed in reduced size, so as to 
render the gross structure of the concretes more readily comparable with the micro- 
photographs of their several mortars, which latter are placed below. In this way the 
internal arrangements of these mixes become visible, even to the smallest particles; 
and be these means the causes of vexatious faults may be determined. When causes 
are known, remedies usually suggest themselves. With the exceptions of the Fuller's 
curve and the 1 : 4 : 8 concrete, the cylinders that were sectioned and polished had been 
tested in compression to the yield point. For convenience with the former and because of 
the weak- nature of 'In- latter, the sectioned cylinders of these two were not crushed, 
compressive strengths being determined on like specimens made at the same time. 

With these two exceptions, therefore, it is possible to see how the several concretes 
bore their load; and low and at wh.'it point they failed a soil of concrete character 
analysis. The areas covered by stones dislodged in grinding were not blacked in, 

because the matrix in which the stones were embedded reveals several important 

matters whi< h it was desired not to Obscure. 
400 



, ToNMUlKTKJNAll f U E 



, mCROSCOPE IS THE STUDY OF CONCRETE. 



HAT THE PHOTOGRAPHS SHOW. 



WHAT in*, r.. al , 8houU ,„. „,„,,, 

These photographs will repa 5 . j^V" „ ,„, .nan. no) onlj between the 





< 






*» 
v 



•fc^JI 






*t .- 



* 







Fi«. 16 Weak Character of Matrix of 1 . 4 . 8 Mix „ 
Flg . 16. uea Isvestigation of Concrete. 

The Microscope in the bTtm 

, • w „ n f email aggregate shown by photo- 
confirmation in gross sections of the ,soUu.. n ««»*■£ [le , s not a theory. It 
Aerographs in Article , The ""dgmgo^ vonfc J^ «£ ^ ^ , Q nl 

is an actual, provoking fact and „U m. n ^ ^ ;„ . bse _ 

adhesion o/ air to aggregate. 1 his questton will be t +0 , 



NATHAX C. JOHNSON. JCQNCBETE J 

quent article. The next feature to which attention is directed is that all of the shear 
planes due to crushing run from pore to pore, whether in the matrix visible between the 
stones, or in that portion which would be covered had all the aggregate remained in 

place. This is but one more bit of evidence as to the pernicious effect of air entrained in 
concrete, as well as additional confirmation of the reasons previously adduced for the 
necessity of using superior aggregate to produce a very inferior product. 

STRENGTH OF THESE MIXES. 

Remembering that the greater the proportion of stone in a concrete, the greater 
its strength and density, it is interesting next to estimate the strength of these several 
mixes, from the appearance of their sections. 

Obviously the hrst of the series, the concrete proportioned according to Fuller's 
curve, or the i : 1*41 : 4^34, shows the greatest proportion of stone. It also is the 
strongest bv test, by a few pounds, 2,420 lb. per square inch at 14 days. (This age 
is 00 early to give strictly representative crushing strengths.) 

Next in order of stone content is 1:2:5, with a strength of 2,280 lb. per square 
inch, as would be expected from the ratio of stone to sand. The others of the series 
hold this ratio constant, so that their surfaces show approximately equal stone areas. 
RATIO OF CEMENT TO AGGREGATE "BURDEN." 

However, the concretes grow progressively weak. If stone content alone were the 
determining factor, this would not prove true, but the question of ratio of cement to 
sand plus stone now demands consideration. In this the photo-micrographs of the 
several mortars, shown in the other two rows of Fig. 15, are of considerable assistance. 

In any concrete, or in any mortar, the function of the cement is not only to coat 
the sand and the stone with an adhesive film, but also to fill all voids between the sand 
particles and the pieces of stone. If the ratio of either or of both of these materials 
to the cement is increased, or decreased, there is a corresponding change in the burden 
on the cement, both as a void filler and as a coverer of surfaces. Bearing this in mind, it 
is no wonder that concretes of different proportions have varying strengths. Since the 
1:1-41: 4-34 concrete has proved to be the strongest, it may be taken as a basis of com- 
parison. If surfaces of aggregate are assumed as proportional to volumes, the ratio of 
cement to surface of sand and stone in this concrete is 1 : 5-75. In the 1:2:5 concrete 
it is 1 : 7. In the 1:2:4 concrete it is 1 : 6; in the 1:3:6 concrete it is 1 : 9 ; and in the 
1 : 4 : X concrete it is 1 : 12. The same ratios should hold approximatelv true for the 
relation of cement to voids. These ratios, together with test strengths of the correspond- 
ing specimens, appear in the following table : — 

Ratio of Strength to Burden Imposed by Aggregate. 
Mixture. Ratio of "burden." Strength, lb. per sq. in. 

Fuller's ... 1 : 5*75 ... 2,420 

1:2:4 ... i:6 ... 2, 2(H) 

1:2:5 ... 1:7 ... 2,2<S() 

[•.3:6 ... 1 : ') ... 1,012 

1:4:8 ... 1:12 ... 590 

MATRIX STRUCTURE. 

'Ihc photo-micrographs of the several mortars al both 15 and 40 powers confirm 
what has before been said. The 1 : ['41 mortar <>f the Fuller 's-curve concrete shows 
plenty of cemenl to coal over and to (ill between the sand grains. The 1 : 2 mortars 
of the 1:2:' and the [12:5 concretes show the same feature, with possibly some- 
thing in favour of the Fuller 's-curve concrete in the matter ol filling voids, due possibly 
to a greater surface-covering demand on the cement, with resultanl thinning of matrix 
layer. The 1 : 3 mortar of 'hi' [ : 3 : 6 concrete shows a weak, faulty structure, full of 
holes and with the voids between the sand grains only partially Riled with cement, 

402 



. c-oN>rkMKTioNAL| 7///.; MICROSCOPE IN THE STUDY OF COXCKKTE. 



as is evidenced bj the dark spaces in the photographs. I he i : .\ mortar oi ih< i : p8 
concrete exhibits the same character, but to a more marked degj . and with a notablj 
less dispersion ot the sand grains relative to one another, due probably to the smaller 
quantity of intrusive, unhydrated cement. And to confirm our reasoning and our 
findings thus far, Fig. [6 shows a portion of the i : 4 : 8 concrete surface, enlarged to 
twice natural size, which maices even more evident the weak character oi this matrix, 
with the sand grains loose and ready to fall out. II careless mixing were to fill such 
a concrete full of air holes, so as still further to weaken it, its fitness for bearing any 
load beyond its own weight mighl properly be called in question. 'I his, however, 
hold- true onlj for concrete made from this particular aggregate. A concrete oi the 
same proportions with different aggregate might be ver) excellent. 

IMPROPER "BURDEN" ON CEMENT. 

In view of the foregoing, it is evident that many of the common defects ol concrete 
are due to the imposing of an improper burden on the cement by poor proportioning. 
Further, arbitrary proportions, or test proportions, thai may be suitable for the use of 

one sand, or for a certain grade of crushed stone, or of hank gravel, may be quite 
the reverse for a different sand and the same stone, or for the same sand and a different 
stone, or for a change in both sand and stone. Each material has surfaces and voids 
peculiar /<> itself, and the quantity of cement must he sufficient to coat these surfaces 
and to fill these voids, with as little in excess as possible, else the matrix layer will be 
either insufficient in quantity or else unduly thick, with the production, in either sase, 
of poor concrete. Arbitrary properties are a shibboleth. Sooner or later they will 
have to be discarded in high-class concrete work; and the sooner this is done the better 
for the industry. Hut poor proportioning of aggregates is not alone responsible for the 
production of poor concrete. In a search for causes as important as that being under- 
taken, " snap-judgments " are to be carefully avoided. In the next paper of this series 
certain other factors in the problem will be studied, with special reference to the light 
thrown upon them by microscopic studies. 

SUMMARY. 
Summarising the preceding discussion, it should be noted: 

1. That the microscope as applied to the study of concrete is not so much a com- 
plicated, scientific instrument as a simple, handy tool, capable of rendering visible 
phenomena and objects beyond the range of unaided vision. 

2. That the minute phenomena observed in microscopic study are repeated in the 
gross ; and that gross sections of actual concretes show the characteristic air voids 
and separation of aggregates that were observed in the mortars previously studied. 

3. That the planes of failure in a crushed concrete run from air void to air void, 
confirming previous reasoning in regard to the weakening effects of such voids, and 
the necessity of employing aggregate of high strength to bridge these points of 
weakness. 

4. That the prevalence of air voids and fissures in the mortar of gross sections 
similar in character to the voids and fissures isolating sand grains in the micro-sections 
previously taken is even greater at surfaces of contact with the large aggregate than 
in other portions of the matrix. 

5. That a concrete having surfaces of aggregate in proper proportion to the 
cement, to be used both as a void filler and as an adhesive, is the best concrete, both in 
strength and density. 

6. That arbitrary proportions mean little, that proper proportions for certain aggre- 
gates do not hold for unlike materials, and that concretes arbitrarily proportioned are 
usually inferior in density and strength. 

7. That a prime factor, though not the only factor, in producing good concrete 
is proper proportioning, and that without this the best materials are rendered valueless. 

4° 3 



K. P. BILLNER. 



llUNCBFXFj 




SOME CONCRETE BRIDGES 

ON THE COLUMBIA 

HIGHWAY, U.S.A. 



By K. P. BILLNER, 

Engineer, Oregon State Highway Commission, Portland, Ore. 

The following article is reproduced from the "Engineering News, " U.S. A., and also 
the line blocks, whilst we are indebted to the author for the photographic illustrations.— ED. 



, j£ SHrrups, 



The Columbia Highway, now being constructed, follows the south bank of the 
Columbia River from Biggs, Ore., through Portland, to Astoria. 

The magnificent scenery along the route, particularly between Portland 
and Hood River, is unsurpassed in this country. Along this portion of 
the highway are numerous mountain streams and ravines w 7 hich had to be 
spanned, and the writer was asked to work out the designs for the 
bridges. In this work it 
has been his aim to 
build structures which 
would harmonise with 
the mighty surround- 
ings and at the same 
time give the factors of 
safety and lew cost 
their due consideration. 



No standard tvpes were &$f- 

I 



16-10 '••/ 

adopted, but reinforced IW^^r 
concrete structures had 
the preference o v e r 
steel bridges. 

Below are given 
descriptions of some of 
the most noteworthy el 
the structures. 




Sec+ion A-B 



Sec+ion o+ Cen4er erf Arch 
I'iti- I. Details of Shepherds Dell Bridge. 
in Bridges on thb Columbia Highway. 



Latoure/Ie Bridge. 

The bridge al La- 
tourelle (Figs. 2 and 3) 
is an original type by the writer, although its principles are borrowed from 
the French expert, the late M. Considere. The principal characteristic of this 

bridge is its lightness. It is 3 1 _> ft. long and 97 ft. high to grade of the road- 
way. It has a 17-h. driveway, and the total width, including two cantilever 

sidewalks and railings, is 25 ft. The concrete above ground amounts to only 

404 



fj r CONSTRUCTION! A (A 
[C\. irNir.im.l.mNC— J 



CONCRETE HIGHWA Y BRIDGES, 



-oo cu yd., making presumabl) the lightesl concrete bridge, relative to its 
dimensions, in this country. It was desired to erect a light structure for several 
reasons, among which the difficult) in securing a firm foundation was foremost 
The underlying bedrock is covered with a layer of sill and boulders to an 




average depth of 25 ft. on the western bank, while on the east side of the creek 
is a deposit of drift sand, 50 ft. in depth. The cost of building abutments and 
piers for a heavy type of bridge would have been very high with these 

conditions of the foundation to contend with. 

405 



K. P. BILLXER. 



IDSseraacEj 



Substructure. — The abutments, as well as the piers, were founded on 
bedrock. The west abutment and the two central column bents were placed 

^ ,g . directly on bedrock. The 

■ -'" r-i-r . east abutment was put on 

four columns, two 4 ft. 
square and two 5 ft. 
square. The average depth 
of these columns is 45 ft. 
from the under r/.de of the 
abutment to the rock. 
The tops of the 5-ft. 
columns are connected to 
the bottoms of the 4-ft. 
c o 1 11 m n s by inclined 
struts, which transmit the 
thrust from the arches 
down to the rock founda- 
tion. 

S 11 p c r s tructure. 
— Each end of the bridge 
consists of two girders, 
which carry a set of 
columns and struts on 
which the roadway is 
erected. This makes a 
cantilever effect, but the 
cantilever action which 
might develop was not 
considered in the calcula- 
tions of the stresses in the 
structure. T h e central 
portion of the bridge con- 
sists of three 80-ft. arch 
spans. Two arch ribs 
carry each span. These 
ribs are 20 in. square 
and are reinforced by 
eight longitudinal 1 -in. 
square bars and hooping 
of 1 S-in . diameter and 
2-in. pitch. The arches 
are parabolic in shape. 
The deck load and any 

superimposed load are 

cairicd to the arch rings 
on vertical columns placed 
ai 10-lt. centres. 




406 



y r CONSTITUTION All 
A KN(. IN 1.1. KINO ^-J 



CONCRETE HIGHWAY BRIDGES. 



To ensure against bending moments in the arch ribs from partial loading 
diagonal members ;\\c erected between the junction points ol the arch ribs 
and the vertical columns and the deck and the columns. These diagonal 




Fig. 4. Bridge at Shepherds Dell. 
Concrete Bridges on the Columbia Highway. 






members are subjected to alternatingly compressive and tensile stresses, and 
therefore special care had to be employed in the construction of the junction 
points. The reinforcing- bars of the diagonals are hooked around the 

4°7 



K. P. BILLNER. 



1CDNQ3E3^1 



longitudinal reinforcement of the arch ribs and also around the longitudinal 
reinforcement of the girders, which form the edges of the deck. Where it was 
found impossible to hook the bars to one another as described, special dowels 





were inserted in the hooks. The joints received a particularly rigid inspection 
during the erection of the bridge. The balustrades are made of artificial stone 

Outline of Calculations. Permissible stresses in the materials were 
assumed as follows: ( oncrete in bending, 600 lb. per sq. in. << mpression ; con- 
crete in direel compression, 500 II). per sq. in. ; hooped concrete in the arch ribs, 

408 



.,CONMl?ljrriONAL 
fv FJMC.INKbWlNd — , 



CONCRETE HIGHWAY BRIDGES, 



750 II). per sq. in. ; steel in tension, [6,000 lb. per sq. in ; steel in shearing, 

io,< 00 lb. per sq. in. 

Loading. A uniform load of too 11). per sq. ft., a concentrated load <>l 
rs tons, and an impact factor of 25 per cent, were adopted. 

The analysis was made for three conditions of loading: First, a uniform 
l oa( j ver the entire bridge; second, half the span of one arch loaded; third, 
two spans were full) loaded, with no load on the third span. 

The springing points 

h 



15 

2 



of the arches wen' re- 
strained from meving by 
making the main columns 
act as beams with double 
reinforcements. 

( 'oust ruction. — The 
falsework was erected 
with a tower at each 
end of the bridge, and a 
cabieway. All of the 
forms were built and 
braced before the con- 
creting of the super- L 
structure commenced. U 0' - 



20-6 : 

Ifctnibrced 

Concrete \ j 



.J' 



Oround 
Line ■ 



fence i Ccr-er/ronProfrrfn/ „ - ,. CT 

>.M ' V5 Cushion j9-\ 



12 




IZ l<.jr-£'->l 



5-6x5-6 ( 
Carrying Area 



Fig. 6. Section of Multnomah Falls Viaduct. 
Concrete Bridges on the Columbia Highway. 



The main columns, which 

are about 90 ft. high, 

were poured in sections 

which were allowed to 

set for a few hours before the next pouring commenced. The arch ribs were 

poured simultaneously, commencing" at the springings and working toward 

the crowns. The deck, containing 250 cu. yd. of concrete, was poured in a 

continuous operation lasting 20 hours. The maximum settlement during the 

pouring of the arches was § in. The deck was poured after the arches had 

set for 12 days. Xo settlement took place while the deck was being poured 

or after. The centres were struck six weeks after the pouring of the arches. 

Bridge at Shepherds Dell. 

This bridge (Figs. 1 and 4) is of a standard type, but has one original 
feature in the reinforcing of the spandrels. The spandrels are reinforced in 
such a way as to make them act as girders, and are capable of sustaining the 
bending moment from the live load over half the span. These spandrels, there- 
fore, will distribute the loading on the arches. The influence of the stiffening 
of the spandrels, although of great value, has not been considered in the deter- 
mination of the dimensions of the arch ribs. The clear spans in the Shepherds 
Dell Bridge are each 100 ft. 

Viaducts. 

Among problems which arose in the construction of the Columbia 
Highway were two which necessitated the building of viaducts. A glance at 
Fig. 6 will be sufficient to explain the situation. The highway here is located 



+°9 



K. P. BILLNER, 



[CONCBEXFJ 



on a steep mountainside, at the foot of which the Oregon-Washington R.R. 
and Navigation Co. 's line is loeated. To exeavate a 24-ft. roadway out of the 
hillside would have meant the moving of an enormous quantity of earth with no 
plaee to dump it. In order to avoid this, the viaducts were erected. 

Fig. 6 shows a cross-section of the viaduct at Multnomah Falls and is 




Fig. 7. Highway Bridge, Multnomah Falls. 
Concrete Bkidges on the Coli mbia Highway. 

typical of the design of these side-hill viaducts. Essentially the construction is 
a solid reinforced concrete slab, crowned to the road crown, which rests on 
transverse floor-beams spanning between columns on the low side and a con- 
tinuous girder on the high side. These columns are Spaced every 20 ft. and 
fool on prismatic bases. The up-hill girder rests on square concrete plates and 
the plates and column footings are tied together by reinforced concrete struts 
410 



j F (.TONSTlHKTIONAi; 
.LMCilNhKPlNCi — , 



CONCRliTK HIGHWAY BRIDGES 



taking the .slope and embedded in ground. Longitudinal stiffness is also given 
by girders at the top of t In- columns under the railing 

Fig, s shows the viaduct from the easl side peculiar arched railing 

should be noted. This type ol railing was us< .1 number of the other 

structures. The total length of these si is [,260 It. Besides eight 

conciete bridges erected on the highwa' » is to 1><- mentioned a footbridge 

ovei the lower Multnomah Palls 5 ft. in the air. This bridge is shown in 
Fig, 8. The total length of roadway of these bridges and viaducts is 2,012 ft. 
The contract price was only $76,500. 

The price per square loot of deck surface varies from $1.25 for the viaducts 
to $ ;; for the high bridges. 




Fig. 8. Footbridge over Lower Multnomah Falls. 
Concrete Bridges on the Columbia Highway. 



I 



4II 



THE CONCRETE INSTITUTE. 



[CQNCREX FJ 




T 



RECENT VIEWS ON 

CONCRETE AND REIN^ 

[ FORCED CONCRETE. 



THE CONCRETE INSTITUTE. 



// is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes, — ED. 




THE CONCRETE INSTITUTE. 

LIME CONCRETE IN THE EAST. 

By E. A. W. PHILLIPS, M.Inst.C.E., M.C.I., 

Retired Superintending Engineer, Burma Public Works Department. 

The following is an Abstract from a Paper read at the sixty-third ordinary general 
meeting of the Concrete Institute. An interesting discussion followed, of which we 
also give a short report. Mr. Chas. F. Marsh, M.Inst.C.E. (Vice-President), was in 

the chair. 

Part I. ORIGINAL PAPER. 

(Presented to the Concrete Institute by E. A. W. Phillips on election.) 

Stone lime of great purity, and consequently non-hydraulic, is used largely in India 
and Burma, and engineers have learnt to place considerable confidence in the material. 
To enable it to set under water it is mixed with " soorkhee," the homra of Egypt.* 
To the present day engineers in India do not know exactly how much soorkhee is 
required by each kind of lime, and this ignorance is due to the want of scientific labora- 
tory tests, of the kind so frequently made in Europe. It seems no advantage to send 
lime and soorkhee to England to be tested, since the difference in climate, the sea 
voyage, and the lapse of time in transit might vitiate the results. t Conservative Indian 
opinion, based on long experience, approves of a mixture of a half-part of under-burnt 
with a half-part of well-burnt soorkhee to one part of slaked lime and one part of sharp, 
clean sand, all measured in bulk, dry. The materials are thoroughly incorporated and 
ground in a mortar-mill, either under one wheel pulled round a circular trough by a 
bullock, or in a pan-machine under a pair of wheels. The mortar should be a thick 
reddish paste, in which the particles of lime cannot be distinguished by the naked eye. 
A mortar made in this way sets very well indeed in still water, but it sets comparatively 
very slowly, and some engineers (the author included) add, when necessary, a propor- 
tion of Portland cement to the mixture. The introduction markedly hastens the setting 
1o an extent depending on the proportion of cement to lime. One part cement to one 
part lime by volume Sets apparently as quickly as cement mortar. In the early stages 
of setting tru- strength of the concrete is much increased, admitting of early handling 
and removal of moulding boards. The addition of cement preserves soorkhee mortar 
in wet foundations from the evils of percolation, and the cement, besides, seems to 
have a i hemi< al ( 7 ) effect on the lime, fixing the particles and aiding in a more solid set. 
First-class soorkhee mortar, several centuries old, it has been asserted, exceeds 
Portland cement mortar, i to \, in strength and impermeability, and is said to he often 
equal to i to ±\. In regard to economy, there is no comparison in Rangoon, cement 

• ogling (1909) about two rupees per CU. ft., and lime only three-tenths of a rupee per 

in. ft. Further, in comparing the two (lasses, it has in he remembered that while 

* -; Soorkhee " in India is finely powdered red brick. 

f Bricks and limestone might, however, be sent, if carefully packed in air- and water- 
tight caw 
41 2 



/, OONXrUUC-TIONA 
«VKN(.lNKt.WlNC. 



g] 



L/AfE CONCRETE IN THE /-AST. 



native Indian masons are exceedingl) clever in dealing with lime, thej often make bad 
mistakes in dealing with Portland cement, and have to be speciallj taught its use, and 
carefully watched besides, as the) arc stupidly stubborn. 

Where a mortar mill cannot be obtained, or when the work is too small to justify 
the expense, stone lime is thoroughly slaked 1>\ being steeped for from twenty-four 
hours to a week or more in fresh water, being kepi constantly covered and stirred up 

at intervals with a rod. The result is a perfectly slaked lime, and a breaking up ot 
all hut the very hard particles. The wet lime is first mixed thoroughly with the sand, 
the particles of the sand tending to still further break up and subdivide the linn-. 
Soorkhee, very finely hand-pounded and screened, is then added in small quantities, 
and if the operation is properly done, it should he a little difficult to detect that the 
mortar has no! been prepared in a mill. 'This is the best native Indian practice when a 
mill cannot he got. Tradition asserts that the stone lime in the Taj Mahal of Agra 
was steeped in water nearly a year before use. 

A suggestion has heen made in Indian Engineering to apply the term " beton " to 
mixtures with both cement and lime, reserving the term " concrete " for the usual 
mixtures. The usual classification for cements and limes is : — 

i. Portland cement. 

2. Natural cement. 

3. Puzzolan cement. 

4. Hydraulic lime. 

5. Common lime. 

With all the above, concretes can be formed, either hydraulic or non-hydraulic, and 
it is proposed that the term " beton " be reserved for all mixtures of 1, 2, or 3, with 
either 4 or 5, in forming mortar. 

The author has employed the following mixtures in practice, obtaining exceedingly 
good, reliable, and economical results in all sorts of places, and especially in bad 
foundations : — - 



Beton, 1 
1 part cement 
1 part lime 
1 part soorkhee 
1 part sand 
6 parts aggregate 



1 : 3 (Equivalent) 



4 (Equivalent). 



■ all measured drv 



all measured drv. 



Beton, 1 : 2 
1 part cement 
1 part lime 
1 part soorkhee 
3 parts sand 
8 parts aggregate- 

Beton, in damp foundations (1:3: 5). 
1 part cement \ 
3 parts lime 

3 parts soorkhee hall measured dry. 
5 parts sand 
20 parts aggregate ( 

In all the above the author employed mjlled mortar if possible, sifting the cement 
in last of all, and thoroughly incorporating it with the mortar, as shown by uniformity 
of change in colour. 

In above-ground work, where the free lime will be air-set, the soorkhee might be 
omitted, in which case two mortars might be made, one lime and sand, and the other 
cement and sand, in any required proportion, and mixed together. 

It is not quite certain, however, that such mixtures will not be set hard even under 
water. The author has made no experiments to prove this. 

In dry climates it is essential to keep hydraulic concrete drenched with water, and 
covered from the direct rays of the sun. The loss of strength in hastily dried concrete 
or beton is enormous ; and nothing is so easy, in the East, as to destroy good material 
in this way. The author speaks feelingly from experience, as he has seen so much 
work, executed with first-class materia], in a thoroughly workmanlike manner, ruined 
because the contractor grudged a trifling expenditure in keeping it wet. Beton especi- 
ally needs slow and long seasoning, and six months is not too long a period in making 
blocks of the 1:3:5 mixture given above. 

The worst form of unskilful handling met with in India is over-ramming. 

Another error is the laying of concrete too dry. With all deference to received 
opinion, the author does not believe in the practical value, in India and Burma, of con- 
crete laid nearly dry and thoroughly rammed. The practice may give excellent results 
in a laboratory, but on work it is bound to fail. The best mixture is a jelly-like mix- 
ture, which can be freely shaken by light ramming, all air displaced, and the material 



d 2 



4'3 



THE CONCRETE INSTITUTE. ICQNCBETEJ 



readily and well settled. Heavy ramming is an absolute mistake. The concrete or 
beton should be laid in small quantities and punned into place, not rammed. If too 
wet, the cement and lime are liable to displacement ; if too dry, the ramming must be 
unduly prolonged, while it is more than probable, in a dry climate, that there will be 
insufficient water in the body of the concrete or beton for proper hydration. External 
watering should be only necessary to prevent evaporation. 

Part II. EXPERIMENTS. 

INTRODUCTION. 

Under this heading the author gave an account of various experiments undertaken 
by himself and others. The Associated Portland Cement Manufacturers (1900) very 
kindlv interested themselves in the matter and gave material assistance, without which 
the experiments could not have been undertaken. 

It seems the Associated Portland Cement Manufacturers have already experimented 
with mixtures of lime and cement, and of lime, cement, and sand. The results are 
most interesting, and were communicated to the author in the following letter : — 

Extract of Letter dated July 28th, 1914. 

" As promised on the telephone, I have been looking up our records in regard 
to the use of hydrated lime in Portland cement concrete, from which I have been able 
to summarise the following information : — 

Effect upon Setting Time. 

Initial. Final. 

Hrs, Min. Hrs. Min. 

Neat cement ... ... ... ... ... ... 1 20 5 30 



90/5 parts cement I 
o'5 slaked lime J 



1 IS 4 



gg'o parts cement | 112 

i'o slaked lime > 
g8'o parts cement » 

2'o slaked lime >' 
95'° parts cement ) 



g8'o parts cement > 
2'o slaked lime )* 



5'o slaked lime t" 

" From these figures you will see that the addition of hydrated lime appears to 
have little effect on the setting time of cement (only slightly quickening it), and these 
results are confirmed by others, which I need not repeat here as the above are fairly 
representative. 

Tensile Strength of Cement Mortar with Various Proportions of Lime Added. 

Lb. per square inch. 
3 parts sand to : — 
1 of cement 
! Q f J 0-05 cement I 

< o'o5 lime ' 

1 of-'°' ( ;' f. ement !- 

< 01 lime > 
x f ( o'8s cement I 

j o' 15 Lime ' 

t ^f ( 0'8o cement '. 

1 o 20 lime ' 

1 of '"'■" '"""" , ,' 

I 30 I II1H- ' 

" It will be seen from these figures that the substitution of hydrated lime for 
more than [5 per cent, of the cement effects an appreciable reduction in the strength 
of the mortar. The results are not concordant, but, on the whole, the use of smaller 
percentages seems to be, if anything, beneficial to the Strength after 28 days. The 
addition of hydrated lime made the mortar work ' fatter,' or freer. 

" We do not appear to have any comprehensive series of crushing tests on lime- 
cement mixtures, but it is 10 be expected thai they would, broadly speaking, follow 

the lines of the tensile tests. 

" The experiments which we have from time to time carried out in connection 
with the waterproofing of Portland cement concrete have shown that the addition of 
a small quantity of slaked lime is, undoubtedly, beneficial in this connection. I 
give you here- the result of one test as an illustration. 
414 



3 days. 
175 


7 days. 
25=; 


28 days. 

263 


3 months 
328 


M3 


198 


2go 


333 


185 


213 


304 


347 


1 44 


222 


330 


382 


no 


193 


241 


309 


83 


183 


200 


238 



,£r^N5-rUUCTTONAT: 



LIME CONCRETE IN THE EAST. 



" Amount of water which percolated during J4 hours, under a pressure ol 50 lb. 
to the sq. in., through .1 slab made with three parts of sand to one o\ cement. 
Firsl slab . . ... ... ... ... no c.c. 

Second slab ... ... ... ... ... 120 ,, 

"5 
" Amount of water which percolated during 24 hours, under a pressure of 50 lb. 
to the sq. in., through a slab made with three parts of sand and one part of a mixture 
of 0*97 cement and 0*03 slaked lime. 

First slab ... ... ... ... ... 4 c.c. 

Second slah ... ... ... ... ... 10 ,, 



THE EXPERIMENTS. 

It was decided to conduct tests on lime and Portland cement concrete at the age of 
six months. In all, some twelve tests were undertaken with mixtures of varying 
composition, some of the materials having been kindly placed at the author's disposal 
by the Associated Portland Cement Manufacturers. It is impossible to give here a 
full account of these tests, but we give below the final analysis of same. 

Part III. CONCLUSIONS. 
CONCRETE TESTS. 

Two sets of tests, Nos. I. and II., were made with beton (1:2:4 equivalent) ; one 
set, No. III., with beton (1:3:5); and one set, No. IV., with a scamped mixture sup- 
posed to be beton (1:3: 5). To compare this beton with Portland cement concrete, two 
more tests were made, No. V. (1:2:4) and No. VI. (1:3: 5). 

ANALYSIS OF CONCRETE TESTS. 













Proportions 






Average 




No. 
of 
















Strength 




















in lb. 


Test 


Sam- 






Cement- 




Mortar, 


Sand 






per sq. in. 


No. 


ples. 


Cement 


Re- 


ing 


Re- 


less 


and 


Mortar 


Coarse 


at 








mainder 


Material 


mainder 


Sand 


Shingle 




Material 


6 months 


I. 


4 


1 


13 


2 


12 3 


11 


6 


8 


2,168 


II. 


4 


1 


13 


2 


12 


3 


11 


6 


8 


1,890 


III. 


5 


1 


3i 


4 


28 


7 


25 


12 


20 


8i7 


IV. 


3 


1 


40 


4 


37 


6 


35 


13 


28 


795 


V. 


2 


1 


6 


1 


6 


1 


6 


3 


4 


3,663 


VI. 


3 


1 


8 


1 


8 


1 


8 


4 


5 


3,n7 



MORTAR TESTS. 

No. VII. — 1 cement, 1 white lime, 1 red soorkhee, 6 sand. 

No. VIII. — 1 cement, 1 grey lime, 1 red soorkhee, 6 sand. 

No. X. — 1 cement, 1 white lime, 1 burnt gault, 6 sand. 

No. XI. — 1 cement, 1 white lime, 1 stock brick, 6 sand. 

No. XII. — No cement, 2 white lime, 2 red soorkhee, 3 sand. 

No. IX. — 1 cement, no lime, no soorkhee, 3 sand. 

The idea was to test 1 : 3 mortars of all kinds as far as possible. It will be noticed 
that the chief difficulty was the classification of soorkhee. Is it part of the sand, or 
part of the mortar, or should it be left out of consideration? 

4*5 



THE CONCRETE INSTITUTE. 

ANALYSIS OF MORTAR TESTS. 



[CONCRETE] 



Test 


No. 
of 
Sam- 
ples. 




A 




Propo 


rtions 

B 






Average 

Strength 

in lb. 














No. 


Cement 


White 
Lime 


Grey 
Lime 


Red 

Soor- 
khee 


Burnt 
Gault 


Stock 
Brick 


Sand 


Pro- 
portion 
A : B 


per sq. in. 

at 
6 months 


VII. 


g 


i 


i 


— 


i 


— 


— 


6 


2 :7 


645 


VIII. 


8 


i 


— 


i 


i 


— 


— 


6 


2 : 7 


488 


X. 


8 


i 


i 


— 


— 


i 


— 


6 


2 : 7 


809 


XI. 


8 


i 


i 


— 


— 


— 


i 


6 


2 : 7 


663 


XII. 


5 


— 


2 


— 


2 


— 


— 


6 


i : 4 


225* 


IX. 


4 


i 





— 


— 


— 


— 


3 


i : 3 


3,051 



* Assumed strength if experiment had been successful. 
REMARKS ON CONCRETE TESTS. 

Unfortunately, there was no time to make tests of lime, sand, and soorkhee con- 
crete. The mixture employed would have been 1 lime, 1 soorkhee, 1 sand, and probably 
6 of shingle, and the results the writer would have anticipated should have been about 
300 to 500 lb. to the sq. in., after six months. Combining the mean of these, say 
400 lb., and the average result of No. V., we get a new average of about 2,000 lb. to 
the sq. in., which agrees pretty well with the average result of the two tests, Nos. I. 
and II. It seems to the writer that if an extended series of tests were made, covering 
the range of 1:2:4 and 1:3:5 variations of mixtures of cement and lime mortars 
from cement mortar at one end to lime mortar at the other, it would be easy to plot 
a curve, which might approximate in the case of concrete to a straight line, to cover 
every possible variation with sufficient accuracy for all practical purposes. If carefully 
carried out, these results would undeniably encourage the employment of cement to 
improve lime concrete at comparatively small cost. Cement has been so employed in 
India since Portland cement was first manufactured. 

REMARKS ON MORTAR TESTS. 

The cement and sand test beats all other tests hollow. The writer does not, 
however, consider that the question has been settled by these experiments. Many more 
experiments are required before it can be stated with any certainty what effect soorkhee 
has on Knglish limes. 

COMPARISONS OF RESULTS. 

Comparisons are difficult on account of this very property of quick setting. Lime 
and sand mortars do not set thoroughly hard for centuries. Cement and sand probably 
attain maximum strength in a few years. The results given in this paper show tests 
at six months. As a matter of fact, a fair comparative test for the beton mixtures 
would have been at six to ten years, to the six months for Portland cement concrete. 

MIXTURES OF CEMENT AND LIME IN THIS COUNTRY. 

These mixtures are not so rare as might be believed. The writer knows of at hast 
one builder who employs the mixture, and he also knows of several instances of pointing 
and walling in private houses, in which a mixture of \ ton cement to every CU. yd. of 
lime was used with astonishingly good results at a few months, with the advantage 
that, although in one case the work was done some ten years ago, the pointing appears 
to be still hardening. The proportion of cement to lime was about 1 : 4. 

THE QUESTION OF COST. 

This is, of course, important. The cost of labour in mixing, handling, and applying 
such mixtures would, with a little experience, he probably the same. If the slower 
416 



[&SSK?S3Sa UME CONCRETE IN THE EAST. 



E.NGINl l-KING- 



setting <I<ms not affect the cost, or other considerations, ii is no disadvantage. Mixing 
lime wiih cement gives a fatter mortar, easier to work. In a countr) w h< re cemenl is 
nearlj as cheap as lime there seems to I" no object in usin^ a mixture, unless it is to 
get a latter anil possibly more water-tighl mortar. Where linn is cheaper than cement 
ii is oleums that in the course of time a mixture of, say, i cement, i lime, i soorkhee, 
ami i) —-.111*1 max be better and more reliable than i cemenl to 4 sand. In the former 
case we get 2 of cementing material to 7 of other material that is, 1 : 3^; in the latter 

ease 1 : j. The soorkhee, too, being as finel) ground as the cemenl and lime, aids lo 

till the interstices of the sand. Claj is recommended for adding to the water-tightness 
of cement concrete. It is a question whether soorkhee would not he better. 

In the East, where carriage is very heavy, when- lime is ihca]) and good, and the 
native masons understand its use better than the use of cement, such mixtures have a 
very high value. 

It is of the highest importance to the structural engineer and to capital that < ement 
can be utilised as described in these pages. In the absence of reliable tests we are all 
working in the dark, by rule of thumb. 

DISCUSSION. 

Mr. D. B. Butler, A.M.lnst.C.E., remarked lhat the use of soorkhee with lime seemed to be 
on a p.u with the use of puozzolana with limes used in Europe. Puozzolana, like soorkhee. was 
really a sort of half-baked clay, more or less burned, and was used to a large extent in Italy 
with lime for work under water. As a matter of fact, he believed that something similar was 
used by Smeaton in the construction of the Eddystone Lighthouse, but that was before 
Portland cement was known. As to the beneficial effect of adding slaked lime in connection 
with the waterproofing of cement concrete, the lime closed the pores, made the mortar work 
latter, and they got a more dense and less porous material. A substance that would set in three 
or four years was preferable to one that took 50 years to obtain its gieatest strength, 
therefore that point would have to be considered very carefully in using lime as against 
Portland cement. 

Mr. Morgan E. Yeatman, M.A., thought that the experiment of adding 3 per cent, of lime 
to prevent percolation might be of value. One often heaid the waterproofness of concrete 
discussed, and its suitability for the side of a reseivoir, or keeping out water for a foundation, 
whether it was necessary to add a waterproof coating of asphalte or something of that sort. 
Possibly this addition of a small proportion of lime might, in some cases, solve the difficulty. 
The experiments did not show that the product of the mixed lime and cement was as good as 
the cement alone would give, but he gathered that cement would be too expensive for use in 
India. He had heard it said that the use of cement concrete in Egypt had not been found 
very satisfactory, and the failure had been attributed in some cases to not keeping it wet in a 
very dry climate. In the dry, hot climates of the East it was very important to keep the 
concrete well damped for some time after setting. 

Mr. A. R. Sage, M.C I., said it seemed worth while to carry the tests further, both from 
a physical and an economical point of view, but that required money, which ought to be 
provided by the Colonial people who were interested in the use of soorkhee. If Portland 
cement could be manufactured in India, the question of soorkhee did not count for very much. 

Mr. W. G. Perkins (District Surveyor for Holborn) said he should be very glad if Mr. 
Phillips would tell them something about the chemical composition of soorkhee. In London 
mortar was frequently compounded with the red bricks that were obtained from the demolition 
of houses from one to two hundred years old These houses were pulled down and the specu- 
lative builder used the old bricks by driving them into a mortar composed of grey lime, 1 to 3 
broken brick. As a rule, provided this lime were properly slaked — and it must be properly 
slaked — they would obtain a very good mortar. These red bricks were very largely used in 
the time of Queen Anne and the Georges, and perhaps previous to that. Mr. Perkins handed 
round samples of these materials, which, he said, had been used by speculative builders, and 
therefore the buildings only just complied with the by-laws. The mixing of lime and cement 
he thought was a very good practice. 

Mr. H. Kempton Dyson (Secretary, Concrete Institute) agreed that the practical tests did 
not go far enough, and that there was plenty of room for more experimenting. A mixture 
of cement with lime had often been used by bricklayers in this country to make it work fatter, 
and it certainly did set well. The tests mentioned in the Paper suggested that there was some 
marked advantage as regarded strength to be derived from such a mixture, and Mr. Phillips 
assured them of its economy 

417 



THE CONCRETE INSTITUTE. {TDNC RSTB 

Mr. H. J. Harding had been associated with the late Mr. George Deacon about 20 or 30 
years ago in the construction of the Burnley and Kendal Waterworks, for which blue lias lime 
was used. The principal thing for all lime was that it must be properly slaked and perfectly 
divided up to the smallest particle. Mr. Deacon carried out the Kendal Waterworks with blue 
lias lime instead of with Portland cement in the face of great opposition, not only on the part 
of engineers, but councillors as well. Some years ago, manufacturers in London introduced a 
ground flagstone mixed with cement, which they sold as cement and which gave a better 
result than pure Portland cement. He did not think that the addition of clay would increase 
the strength of concrete. Something harder than clay, if ground as fine, would be much better 
than clay itself. 

Mr. Allan Graham, A.R.I. B. A., observed that, in our Colonies, where Portland cement was 
difficult to obtain, these experiments would be of considerable value. It certainly was an eye- 
opener that the addition of a little lime to the concrete, and with so much aggregate added, 
seemed to reduce the concrete so little from the pure Portland cement concrete For that reason 
there was something in this line of research. What had been said about the addition of clay 
to concrete was the recrudescence of an old heresy when Portland cement was a different 
material from what it was to-day. It might be used for the sake of economy for mass concrete 
where they did not require the great strength that reinforced concrete demanded. 

Mr. A. Stewart Buckle, M.S.E., who was in Assam at the time of the great earthquake in 
1897, gave some of the results of his experiences in railway reconstruction there. He suggested 
that Mr. Phillips might adopt the accepted spelling of Hindustani words, and call it " surkhi." 

The Chairman had great faith in adding lime to concrete to increase its watertightness. 
He generally used 5 per cent, of hydrated lime, and found it had a considerable effect in 
reducing the percolation of water ; in fact, in some cases it was a good deal better than most of 
the patent compounds that were sold. He believed it was merely a case of filling up the 
interstices. In the tests which had been carried out, apparently the grey lime had not been 
slaked before use, consequently it had yielded extremely bad results. In America there was 
a very strong section of opinion that very finely divided clay was a good material to add to 
increase the watertightness of concrete. The difficulty with clay was that they must be very 
careful what clay they used, and very careful tests ought to be made before they used it. No 
doubt the late Mr. Deacon used blue lias lime because he was building a big masonry dam, 
and he wished it to set evenly. His fear was that if he used cement he would get cracks, as 
one part of the dam might set hard before the other part had settled down ; therefore he used, 
and advocated the use, all through his life, of blue lias lime for masonry dams so that the 
setting might take longer and the dam settle itself in that particular place without cracking. 

MR. PHILLIPS'S REPLY. 

In reply, the author explained that he did not recommend the employment of clay to add 
to the watertightness of concrete ; he advocated the use of soorkhee, which he considered would 
be better. He was in entire agreement with the suggestion that further tests should be made. 
These might easily continue over a period of four or five years, and even then they would not 
get to the bottom of the subject. He undertook to contribute to the Transactions of the 
Institute a considered reply to the various criticisms. 



418 



'j^OONM'PIKTIONAI. 
t\KM(ilNhl-.KlNti — . 



REINFORCED CONCRETE BRIDGE. 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable Information ivill be presented of neiv ivorks in course 0/ 
construction or completed, And the examples selected ivill te from all parts of the "world. 
It is not the intention to describe these ivorks in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea ivhich serued as a basis 
for the design. — ED. 



REINFORCED CONCRETE BRIDGE OVER THE RIVER CALDER, AT STERNE 
MILLS, NEAR SOWERBY BRIDGE, HALIFAX, YORKSHIRE. 

The illustrations which we arc herewith reproducing show a reinforced concrete road 
bridge constructed on the Coignet system over the River ('alder at aterne Mills, near 
Halifax. This bridge was constructed to replace an old iron and timber bridge, the 
object being to supply a better means of conveying across the river heavy traffic. 

The bridge is a private one, having a right of way for foot and bridle traffic 
across it, and it unites some property in the ownership of Air. A. E. Carroll, for whom 
the new bridge was constructed. 

Messrs. Jackson and Fox, of Halifax, were the architects responsible for the 
abutment works, which were carried out in masonry with concrete foundations, and 
for the laying of the roadway, and also for the general supervision of the construction 
of the reinforced concrete works, the design and plans of which were prepared by 
Messrs. Edmond Coignet, Ltd., of 20, Victoria Street, Westminster, who were the 
engineers responsible for the reinforced concrete work. 

Owing to the soft nature of the foundations encountered at the abutments, it was 
found necessary to keep as much as possible of the weight and loads of the main beams 
from bearing upon the masonry of the abutments, and this was effected by introducing 
two extra reinforced concrete piles to support the main beams a; the north abutment, 
and two extra ones, united by a vertical reinforced concrete slab, at a position adjoining 
the south abutment ; and a nearly horizontal reinforced concrete floor slab was put to 
connect this to the south abutment masonry. There is an opening of 6 ft. between the 
masonry of the south abutment and the adjoining piles to form a storm water overflow 
and give additional waterway in the case of floods. 

The bridge is composed of three almost equal spans and the storm water overflow, 
the middle span being 32 ft. 4 in. centres, and the two adjoining spans being 31 ft. 10 in. 
respectively, and the storm water overflow 6 ft., giving a total length of 96 ft. between 
the abutment piles, or about 103 ft. 4 in. between the abutments. The width of the 
bridge, measured from the inside face of the parapets, is 10 ft., and a 12-in. stone kerb 
has been provided on either side and stone setts form the roadway. 

As this bridge is only for rural purposes, it was not deemed necessary to make it 
very wide or to provide for footpaths, the main object being to obtain a strong and 
economical structure. As the River Calder is subject to a considerable rise at certain 
times of the year, it was necessary to allow for as much water-way as possible, and 
the two intermediate piers, which are constructed on reinforced concrete piles, have been 
heavily braced as a protection against a strong current and any shock due to floating 
timber. 

The piles were driven, some by means of a steam pile driver, but most by hand 
power, to an average set of 1^ in. in the last ten blows of a 2-ton monkey falling from 
a height of 4 ft., and the average length of the piles from water level to point of pile 
is about 24 ft. 

The bridge was tested by means of a heavy steam waggon and trailer, and 
practically no deflection whatever was noticed. 

A timber bridge was erected temporarily to provide for foot and bridle traffic during 
the reconstruction of the bridge. 

4-*9 



NEW WORKS IN CONCRETE. 



[CONCRETE) 



The contractors responsible for the execution of the work were the Yorkshire 
Coignet Contracting- Co. (Messrs. Henry Atkinson and Sons, Ltd.), of Leeds. 




Finished Bridge. 




Bridge in course of construction, 
Reinforced Concrete Bridge over the River Calder, Vorks. 

NEW OFFICES FOR THE INDO-CHINA BANK. SINGAPORE. 

The new premises of the Banque de I'Indo-Chine, completed last year, are the first 
reinforced concrete buildings in Singapore. They arc situated in Raffles Square, the 
centre of the town, where many old buildings have recently been demolished and 
replai ed by new. 

420 



'j.OON.VTkniCTIONAr 
■ Eys'CilMt-.r-KINli — 



The total ai 



REINFORCED CONCRETE IN SINGAPORE. 

ea of the site is about 4,000 sq. ft., and the ground is good, being 



chiefly hard clay and rock. 

The design of the buildings is not \\< 



.11 su ited to reinforced concrete, the original 



,,.., z-;;:t::: ,:• '^ -■■■< *& > ' «■ "T"""; 1 sfS Than 

Refnfo^d concrete was ultimatel) employed, as its cost was substantial!) less than 







that of the lowest steel structure tender, but the general disposition of the building 
had to be maintained and the best possible use made of it. ,,^1^:^ 

The reinforced concrete structure comprises a general skeleton from the foundations 
the pillars being imbedded in the brick piers and walls. The floors also are reinforced 



NEW WORKS IN CONCRETE. 



10QNCBETE1 



concrete, the ground floor being specially reinforced in the centre, which forms the 
top of the strong room. . 

As soon as the first floor had been put into position, the bank took possession ot 
the ground floor, and its business was carried on there during the erection of the 
remainder of the building. The first floor has a thickness of 5 in. only, the top inch 




being 1-2 cement plaster, which was laid on the concrete directly the latter had been 
plaoed in position, and which thus forms a part of the floor. A dwarf wall was 
placed around the edge of this floor, which was then flooded with water and kept 
flooded for three months, when the roof of the building was completed. Fig. 1 shows 



4.22 



fit, CONM 



unrnoNAi. 

NC.l.NKL.WINti — , 



REINFORCED CONCRETE IN SINGAPORE. 



the floor In this condition, and was taken when business was being transacted in the 
offices of the bank below in the ordinary way. 

All the floors, staircases, lifl stancheons, lintels, ties, etc., are of reinforced concrete, 
and so also are the roof trusses, which require no maintenance and are no more 
expensh «• than steel trusses. 

'The design of the ceilings, being somewhat elaborate, allowed reinforced concrete 




Fij4. 3. Finished Building. 
New Offices for the Indo-China Bank. Singapore. 

to show its adaptability to advantage. The main beams are 4 ft. deep and carry light 
brick filling, forming cornices. All ornamental work was cast in concrete moulds, 
concrete being used for external features and plaster-of-paris for internal. This is 
another new departure for Singapore, ornaments having previously all been made one 
by one and uniformity being therefore conspicuous by its absence. 

The architect of the building was Mr. D. McLeod Craik, A.R.I.B.A., of Messrs. 
Swan and Maclaren, Singapore, and the contractors were Messrs. Brossard and Mopin, 
of Saigon, the whole structure being calculated and erected bv their Singapore agent, 
Mr. P. H. Barriere. 

423 



NEW BOOKS. 



[CONCKETFJ 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books which have appeared during the last fevj months. 



Construction of Masonry Dams. By Chester 
W. Smith. 

London: The Hill Publishing Co., Ltd., 6 & 8 Bouverie 
Street, London, E.C. 279pp. + xi. Price 12/6 net. 

Contents. — Exploring the Site — Temporary 
Works for Stream Diversion — Pre- 
paring the Foundation — Masonry Con- 
struction — Quarrying — Face Work — 
Miscellaneous Features — Plant and 
Power — Installation Required and 
Power Consumption — Assembling 
Materials, Crushing and Mixing — 
Transportation of Materials — Pro- 
bable Future Methods — Estimates of 
Cost — Partial List of Existing Dams, 
with Descriptions and Costs. 
The author of this volume states that of 
all the structures designed and built by 
engineers, a masonry dam is probably the 
one about which there is the least amount 
of exact knowledge, and he gives his 
reasons for the statement and expresses 
them in a clear manner. The book is very 
practical in character, and the various 
aspects of the subject are dealt with in 
detail ; thus the matter should be of value 
to engineers who are engaged in the 
design and construction of dams. The 
necessity of obtaining a thorough know- 
ledge of the foundation is first con- 
sidered, and notes are given which deal 
with borings ; and this is followed by 
examples and types of diversion works 
and the preparation of the foundation. 
After describing the general construction 
of dams, the author gives two chapters on 
miscellaneous features, and these are pro- 
bably the most interesting, if not also the 
mosl instructive, in the treatise. Such 
matters as uplift pressure, expansion 
joints, ice thrust, and initial stress are 
included under this heading, and actual 
examples are quoted when necessary to 
emphasise any particular point. 

Many well-known dams are described 
in the lasl chapter, the descriptions being 
accompanied by drawings and photo- 
graphs, together with details of the cost. 
The book- is well written and fully illus- 
trated, and we consider that the author 
has produced a comprehensive treatise 
which does justice to the subject, and we 
can thoroughly recommend it to our 
readers. 



Plain and Reinforced Concrete Arches. By 
J. Melan. Translated by D. B. Steinmau, 
C.E., Ph.D. 

London: Chapman and Hall, Ltd., 11 Henrietta Street, 
W.C. lbl pp. demy tvo. Price 8/6. 

The book under review is a translation 
of the article by Professor Melan pub- 
lished in F. von Emperger's Handbuch 
fur Eisenbetonbau, and contains the 
treatment of many problems that we have 
not seen dealt with in any other books on 
the subject. 

The first five chapters deal with the con- 
ditions of stability of various arches for 
vertical loads derived from the elastic 
theory, and do not differ greatly from the 
usual mathematical treatment. The next 
chapter gives a brief treatment upon non- 
vertical loads. 

Chapter VII. is upon approximate 
methods for the hingeless arch based upon 
the useful rule that the total area between 
the centre line of the arch and the line of 
pressure must be practically zero ; from 
this he obtains a very useful result for the 
maximum bending moments for a uniform 
load over half the span. The next three 
chapters deal respectively with two-hinged 
and one-hinged arches, arches with elastic 
abutments, and the effect of continuity of 
arches. 

Chapters XI. and XII. contain investi- 
gations of the determination of the best 
curve for and thickness for an arch, and 
one based upon a differential equation for 
the elastic line. A similar treatment has 
been given by Prof. Lilly, of Dublin, and 
deserves further recognition. The final 
chapter deals with the proportioning of 
reinforced concrete arches, and contains 
two worked examples and an interesting 
chart for facilitating the design of doubly- 
reinforced beams. 

The book will undoubtedly be of con- 
siderable assistance to engineers who are 
already familiar with the formulae result- 
ing from the elastic theory of arches, and 
have sufficient facility in mathematical 
manipulation to follow the development of 

i he formulas for the special cases under 
( on >id iral ion. 
A large number of engineers, however, 

will in our opinion find the book very 
difficull to follow on account of the com- 



424 






(ggjgggB^ Ny<;u ' BOOKS. 

parative lack of explanation "I 1 1 1 < • mathe- reinforced concrete arches conditions thai 
matical formulae; while ii is true that can be only approximate in practii 
some numerical examples are given, the In the case of the steel arch, the stati- 
explanation of such examples is rather cal indetermination of the forces necessi- 
meagre, and as a rule mere reference is tates assumption as to the fixity of the 
given by way of number to the mathe- ends and the deformation under stress, 
matical formulae. small departures from which have a con- 
While recognising fully the difficulty of siderable effect upon the results obtained; 
the task, we think there is still great in the reinforced concrete arch we have, in 
need of a hook which develops simpler addition to these difficulties, the inaccu- 
formulae that will express the results of racy due to the variation in the properties 
the standard eases of loading with suffi- ol the material and its effect upon the 
cient accuracy, making allowance foa the distribution of stresses in a doubly-rein- 
necessary errors involved in applying to forced beam. 



425 



MEMORANDA. 




Memoranda and Neivs Items are presented under this heading, ivith occasional editorial 
comment. Authentic neivs "Will be ivelcome. — ED. 



The L.C.C. Regulations with respect to the Construction of Buildings wholly 
or partly of Reinforced Concrete.— At a meeting of the L.C.C. held last month 
the question of the regulations regarding reinforeed concrete was under further 
discussion. The regulations as originally drafted have undergone considerable revision, 
and the regulations as revised were published in the Council's agenda of July 6th. 

We give below a copy of the report of the Building Acts Committee as follows :— 

On November 21st, 191 1 (pp. 1170-1 and 1175-88), the Council, under the authority 
conferred on it by Section 23 of the London County Council (General Powers) Act, 1909, 
made regulations with respect to the construction of buildings wholly or partlv of 
reinforced concrete. The regulations were prepared after consultation with the 
Institution of Civil Engineers, the Rovai Institute of British Architects, the Surveyors' 
Institution, the Concrete Institute, and other associations and committees interested 
in the matter. The regulations, having been made by the Council, were submitted to 
the Local Government Board for allowance. After prolonged negotiations with the 
Board a revised draft of the regulations was prepared, and the Council on June 24th, 
1913 (p. 1499), made regulations in accordance with this draft. The amended regulations 
were submitted to the Board for allowance, and in accordance with the provisions of 
the Act the four institutions before mentioned were informed of the Council's intention 
to apply for the allowance of the Board. Further negotiations have taken place with 
the Board and the institutions, and numerous suggestions for modifications in the 
regulations have been received. We think that a large number of these suggestions 
might be adopted, and we have accordingly prepared and now submit a revised set of 
regulations. The Local Government Board has stated that in its opinion the 
regulations as now amended might properly be allowed, and the Royal Institute ot 
British Architects has placed on record its opinion of the great value of the regulations 
to architects not only in London, but throughout the whole of the Empire. 

The regulations as now amended are less onerous than those made on June 24th, 
1913, and more in line with the regulations made on November 21st, 191 1. If, as the 
result of experience gained during the next few years, it should be found that 
alterations are desirable, there should be no difficulty in modifying the regulations. 

In addition to the notice required by Section 23 (4) of the Act to be given to the 
above-mentioned institutions, the Local Government Board desires that, as in the case 
of by-laws to which Section 184 of the Public Health Act, 1875, applies, notice should 
be advertised in one or more London newspapers, preferably daily papers, .and in one 
of the technical papers circulating amongst persons professionally or commercially 
interested or affected. The Board also desires that a copy of the regulations may be 
deposited for inspection ;it tin- offices of the Council for a clear calendar month after 
the publication of the advertisements and before the submission of the application to 
the Board for the allowance of the regulations. 

If the Council approves the regulations, it will be necessary for them to be confirmed 

at a subsequent meeting. We recommend: — 

(a) That the resolution (No. i/>) of June 24th, [913 (p. 1499), making regulations 
with respect to the construction of buildings wholly or partly of reinforced concrete 
and with respe< I to the use and composition of reinforced concrete in such construction, 
and the further resolution (No. 5) of July 1st, 1913 (p. 3), confirming the same, be 
rescinded. 

(b) Thai, pursuant to the provisions of Section 23 of the London County Council 
426 



lAFjM(.INhF.mN(i — ; 



MEMORANDA 



(General Powers) Act, [909, regulations with respect to the construction "I buildings 
wholly i, i' partly of reinforced concrete and with respect to the use and composition 
of reinforced concrete in such construction, he made as follows: 

[The regulations referred to will he published next month.) 

i, i I'll; it notice be given to the Royal Institute oi British Architects, the Surveyors' 
Institution, the Institution of Civil Engineers, and the Concrete Institute oi the 
Council's intention in apply to the Local Government Board for allowance <»f the 
regulations specified in the foregoing resolution (b), and that notice he advertised in 
daily newspapers and technical papers circulating in London. 

((/) That, on the confirmation of the regulations specified in the foregoing 
resolution <(b) and after the expiration "I one calendar month from the date of the 
appearance of the advertisements specified in the foregoing resolution (c), the qecessary 
steps he taken to ohtain the allowance of the regulations by the Local Government 
Hoard, and that the Board he asked to fix a dale on which the regulations shall come 
into force. 

A discussion took place on the report. Mr. Bernard Holland (Chairman of the 
Housing Committee) said that the report of the Committee ought to have been brought 
up in plain and clear language, so as to enable any member to understand the effect 
the regulations would have on the Council's dwellings for the working classes. lie also 
asked whether the regulations would tend to increase the cost of buildings. 

Major Levita enquired whether Government buildings in which reinforced concrete 
was used would he subject to the regulations. He thought the Government would not 
accept the regulations. 

Mi'. A. T. Taylor said the regulations only applied to large six, seven, or eight- 
storey buildings. 

Mr. Dove did not think the regulations would affect workmen's dwellings at all. 
He thought the Council might let the report go through for what it was worth. 

The report of the Committee and the regulations were adopted. 

Concrete Blocks at Fishguard.— The accompanying illustration shows a concrete 




block being laid in position by the " Titan '.' crane in order to reinforce the breakwater in 
connection with the Fishguard Harbour Station. 

•. -;',-" 4 2 7 




CONCEETEK 



CONSTRUCnONAIS 
ENGINEERING — ' 





The above is a photograph of three complete Pile Driving Plants, 
as supplied by us to the Belgian Government lately. They were 
equipped with our 2-ton Single-acting Steam Hammers, 5-ton 
Double-barrelled Winches, and the pile driving frames were 
55 ft. each. 

When wanting reliable Pile Driving Plant for any purpose, 
send us your enquiries. Everything available for sale or hire, 
and immediate deliveries given from stock. 



Weights of Piling on sale or hire :— 
SIMPLEX " - 22 to 27 lbs. per sq. ft. 

UNIVERSAL: JOIST" from 43 lbs. 



t» 




Please mention this Journal ''wJten Uirtttng, 



r/^oN>iu'ur.ioNAii memoranda. 

The National Road Exhibition, — In connection with the National Road Con- 
ference, which was held al the end <>i June, there was an exhibition <>! road materials. 
Quite a number "I firms exhibited, and we would speciall) refer to the exhibits <>| the 
following : — 

British Reinforced Concrete Engineering Co., I. hi., who showed their road 
fabric, consisting of a drawn-stee] wire mesh, which is electrically welded wherever the 
w ires cross. 

Ransome VerMehr Machinery ('<>., I. hi., Brunswick House, Westminster, S.W., 
showed one of their well-known concrete mixers speciall) designed for comparative!) 
small jobs. The} also exhibited several lengths of their steel piling. 

Sharp, Jones <*>/</ Co., Parkstone, Dorset, showed ihrir patent rock concrete tubes 
for sew eis and culverts ami their Aqualite manholes. 

Stotheri and Pitt, Limited, 38, Victoria Street, S.W., also exhibited a mixer known 
as the " Smith" mixer, capable of mixing either tar macadam or concrete. 

Trussed Concrete Steel Co., I. id., Caxton 1 louse, Westminster. The principal 
exhibit of this firm was their "lly-rib" steel sheeting and "Atlas" reinforcement 
for concrete road beds. 

United States Steel Product Co., 36-38, New Broad Street, exhibited their triangle 
mesh concrete reinforcement. 

George F. West Co.. Caxton Mouse, Westminster, exhibited their lock woven 
mesh for concrete reinforcement, as also samples of woven wire fencing. 

All the exhibits have been described in detail from time to time in these columns. 

Tire Exhibition was opened by the President of the Local Governmenl Board, the 
Rt. Hon. Walter bono, M.p. 

PROPOSED NEW WORKS. 

Rochester. — Tenders have been invited by the Corporation for enclosing a railway 
arch with reinforced concrete to serve as a fire-engine station. 

Sunderland. — By the Weardale and Consett Water Co. 's Rill, which has been 
passed by the House of Lords, it is proposed to construct a reservoir at an estimated 
cost of ^400,000. 

Tynemouth. — As the result of an agreement arrived at before a Parliamentary 
Committee, on the Water Hill of the Ashington Urban District Council, the Tyne- 
mouth Corporation have undertaken to promote a Bill for authority to construct a 
reservoir of a capacity of 2,000,000 gallons. 

Mull. — Tenders have been called for during the month by the Corporation for re- 
inforced concrete work in connection with the extension of the boiler plant at the 
electricity works. 

Pirbright. — The Guildford Rural District Council have invited tenders for a 
bridge, with concrete abutments, over the canal at Pirbright. 

Edinburgh.— In connection with the erection of their new generating station at 
Portobello, the Edinburgh Corporation have this month called for tenders for concrete 
foundation work, steel reinforcement, concrete piles, etc. 

llminster. — The Somerset County Council are rebuilding Hem Bridge with a 
reinforced concrete arch, 13 ft. 6 in. in span, and have called for tenders for the work. 

Durham. — Amongst the tenders called for during the month are three by the 
Durham County Council for laying reinforced concrete foundations on three sections 
of the Durham-Gateshead main road. 

Rochdale. — The Water Committee propose constructing a reinforced concrete 
bridge at Cown. 

Hastings. — Plans have been allowed by the Corporation for reinforced concrete 
foundations for the new block of the East Sussex Hospital. Mr. B. Green is the 
consulting engineer 

Merthyr Tydfil. — In connection with the waterworks extension of the Corporation 
tenders have been invited lor a concrete balancing tank. Sir Alexander Binnie, Son, 
and Deacon are the engineers. 

TENDERS ACCEPTED. 

Colch es te r. — The Essex County Council have accepted the tender of Messrs. 
Myall Bros., Southend, of ^882, for the construction of a reinforced concrete tank 
at Severells Asylum. 

4.29 



MEMORANDA. 



[CONCRETE] 



New Canadian Dock. — It is reported by the Imperial Trade Correspondent at 
Toronto that a new dock built by the Canadian Government, at a cost of ^13,360, 
lias been opened at Windsor, Ontario. The dock is of concrete throughout, and is 
( 65 ft. long. 

Openings in Shanghai. — 1I.M. Consul at Shanghai reports that it would be an 
advantage if some United Kingdom manufacturers would place stocks of bars, etc., 
in the hands of reliable representatives in Shanghai, and especially mild steel bars 
for reinforced concrete work, for which there is a constant and growing demand. 

ERRATUM. 

Recent Views: Stability of Quay Walls.— In our issue last month, page 363, 
we regret that in reporting the remarks made by Mr. Chas. F. Marsh, M.Inst.C.E., 
the latter part of his speech was inadequately reported. The report read : " Personally 
he should be perfectly satisfied with a factor of safety of ri." 

His statement should have read as follows :".... If it were possible that all 

conditions, both external ami internal, could be known, then a factor of safety of vi 

would be sufficient/* 

TRADE NOTICES. 

"Lapidolith." — " Lapidolith " is the name given to a colourless liquid compound 
which the makers claim wear-proofs and dust-proofs concrete floors permanently. Full 
particulars of this preparation can be obtained from the sole agents, Messrs. W. Mac- 
donald and Co., Ltd., 23, Strutt Street, Manchester. 

Waverley Book Co. — We understand that the Waverley Book Co. are giving away 
a sectional model of a building in reinforced concrete with every copy bought of their 
work on that important subject. " Reinforced Concrete," we are informed, is complete 
in one useful volume, and every section is written by a specialist, thus rendering the work 
one of the most complete and up-to-date publications on construction in concrete-steel on 
the market. It is supplied on terms that may be advantageous to those who are suffering 
temporarily from the effects of the war. We believe that the special offer of the 
sectional model is for a limited period only, so that any of our readers desiring further 
information should send a postcard, mentioning Concrete and Constructional 
Engineering, to the Waverley Book Co., Ltd., 7, 8, and 9, Old Bailey, London, E.C., 
a>kin<4 for their useful free descriptive pamphlet. 




THE 

VICTORIA 

CONCRETE MIXER 

1. Centre Ring Construction. 

2. External Discharge Chute. 

3. Drum J-in. Steel Plate. 



The VICTORIA is designed for fast and 

efficient mixing. It will mix concrete faster 

than you can get rid of it. 



The VICTORIA 



is built to last 



WRITE FOR CATALOGUE No. 29. 



THE 



T. L. SMITH Co. 

13, Victoria Street, S.W. 



430 



Please mention this Journal -when "writing. 




W PC 
Z -S, 



W 






CONCRETE 



Volume X. No. 9. London, SEPTEMBER, 1915. 

EDITORIAL NOTES. 



THE NEED FOR RESEARCH WORK. 

Elsewhere in this issue we give a short review of the Report for the year 

i c) 1 4- 1 5 issued b\ the National Physical Laboratory, and a general idea of the 
work accomplished by the Engineering Department can be gathered from this 
review. 

The question ol research work is, however, of such primary importance 
that we take this opportunity of putting before our readers a few observa- 
tions in the hope of stimulating- more interest in the subject and thus possibly 
assisting in the future development of scientific investigation. The work 
actually done by the National Physical Laboratory is to be hig-hly commended, 
and it is gratifying to find that the tests made in connection with the strength 
of materials alone for the past year number 241 as compared with 167 for the 
previous year, while the work proposed for the following- year promises to be 
very useful, more especially to engineers, as the testing- of reinforced concrete 
is included in the programme. The work, however, has been hampered by 
lack of funds, and it is a great pity to find that so little practical assistance is 
given by the State. The Laboratory fills a great need in this country, and yet 
it is not properly supported, with the consequence that it becomes necessary to 
send a letter to the Prime Minister asking- him to receive a deputation to lay 
before him reasons for relieving the Royal Society from the financial responsi- 
bility involved in their control of the Laboratory and for placing- the Committee 
in a position to carry out work urgently required by granting- increased support 
from public funds. A Memorandum was drawn up, and this was sent, "with a 
letter, to Mr. Asquith in July, 1914. The receipt of these were acknowledged, 
but the outbreak of war prevented further action. The financial position was 
so adversely affected, however, during the early months of the war that the 
Committee felt compelled to approach the Treasury for some assurance of 
support. It must be remembered that the Laboratory has been and is doing 
a great deal of useful work for the Admiralty and War Office during this 
critical time, and this fact alone is sufficient to justify generous support; while, 
apart from this consideration, we have before us the absolute necessity of 
making- all possible progress in every branch of scientific research in order that 
we may successfully compete with other nations in all the world's industries, 
and there is no doubt that we have slumbered too long in this respect. 

The Germans have probably realised more fully than any other nation the 
necessity of assisting- their industries by scientific experiments, and thev 
rightly consider that important improvements in any industrial process cannot 
be expected before exhaustive scientific research has been undertaken. The 

B 43 ' 



THE NEED FOR RESEARCH WORK. [CONCRET E! 



Americans have also advanced in this respect, and the Bureau of Standards at 
Washington, U.S.A., receives an annual grant of ^'100,000 from the Govern- 
ment, and again in France they are advanced far beyond Great Britain as 
regards research work. There are plenty of clever men in this country, but 
there appears to be a great deal of conservatism in Great Britain, and we 
always take a very long- time before a real start is made in any step of advance- 
ment, the tendency to follow rather than lead being- one of our greatest weak- 
nesses. 

Numerous questions are waiting- to be investigated in relation to the 
building industry alone, and the need of research work was never more apparent 
than at the present time, when the application of scientific methods to building 
construction is being followed by engineers generally. The research work 
should, as far as possible, be conducted with the view of producing results of 
practical use in everyday work, and furthermore the investigations should be 
exhaustive and carried on to a definite end. A great number of experiments 
have been conducted in what may be termed a half-hearted manner, and the 
results are published in an incomplete form, so that very little benefit is con- 
ferred on the community. Again it would be advisable to devote our energies 
to those problems which have not been fully dealt with in other countries pre- 
viously, and thus an endeavour made to produce new information of a useful 
character. 

Research work is extremely interesting, and the investigator is usually 
well recompensed for his labours without regard to the actual money received ; 
but it is unfortunately impossible to conduct experiments without going to 
some considerable expense, and it is only when funds are not limited that the 
best work can be done. The results of scientific investigation are of benefit to 
the whole of the nation, as they tend towards efficient and economical industry, 
and for this reason the National Physical Laboratory should be aided by the 
State and encouragement given in every way. Research work in relation to 
the scientific application of materials in building work has been greatly neglected 
in this country in the past, despite its great importance, and we hope that in 
the near future steps will be taken to deal seriously with the question by a 
real organisation of the powers and talent possessed by the various institutes 
connected with the building industry. 

We certainly consider it the duty of the Treasury to assist the National 
Physical Laboratory liberally, and no question of war economies should be 
allowed to affect the work and the developments of this splendid institution. 
In fact, any parsimony on the part of the Government towards any of the 
.scientific bodies or testing stations would be fatal. Where they meet with 
difficulties owing to the war they should be temporarily assisted with sub- 
stantial grants, nol only to carry on their useful work, but to prepare for the 
many problems that will arise in technical matters when the war nears its 
conclusion. 

When peace has been declared we musi be prepared for another form 
of warfare — namely, that of economics and industrial expansion, and we 
shall be hopelessly l>< ateh if we allow our technical institutions to be hampered 
for lack of funds in the meantime. 

432 




[AS^n^Vi'n^?] effect of reinforced concrete on design 

■ ILL J-i >H\t tk, i\ .-i^tv.-: W§ji 5 

THE EFFECT OF REIN- jfc 
FORCED CONCRETE UPON i£ 
ARCHITECTURAL DESIGN £ 



By FRANK H. HEAVEN, A.R.I.B.A. 



The question of the effect of reinforced concrete 
upon architectural design is one of great importance 
and nve trust, therefore, that thefolloiving article may prove of interest and use.— ED. 

The introduction and general use of any new material into the construction of 
building's must, ipso facto, have its influence upon the architectural design of 
those buildings. 

Reinforced concrete has now been in almost universal use for the past ten 
years or so, and its influence upon architectural design can be analysed by any 
person possessing - an observant and retentive mind. It can be traced in the 
design of any building of size or importance by comparing first, its plan in the 
spacing and size of the points of support of superincumbent l